Best Yet! My only complaint there, is I wish his fur had the same golden hue that it did in PC. But he didn't randomly switch colors like in LWW (ie the lighting was more realistic) and his expressions were more realistic than they were in PC. (By the way I started a similar thread to this in the Characters section a while ago, but it might be slightly different....)

1) LWW, 2) VDT, 3) PC

LWW: Good. Occasionally incredible.

PC: Fine. Occasionally dreadful.

VDT: Consistently decent.

I voted for option 1. VDT, 2. PC, 3. LWW. I thought that the consistency factor was higher in VDT than in the first 2 movies. Also, I really liked the shot of Aslan near the river in PC a lot so that's why I gave PC the edge over LWW.

Interesting topic. I've always wanted to give my input on this. Aslan's CGI has changed quite a bit throughout these three movies. Here's my point of view on it all.

The Lion, The Witch and The Wardrobe
Aslan looked like an actual lion: like a lion you could see in real life. Some of the minor problem were the eyes and the mane. There's just something about the eyes in certain shots that looked somewhat strange And the mane in certain windy scenes looked somewhat odd. Nothing really noticeable though. One final thing is that when the witch asks Aslan "How do I know your promise will be kept?", Aslan roars. The roar is just, uuhm... Ah yeah, the roar is just "uuhm?". Overall, I really liked the look of Aslan in LWW though.
http://tinyurl.com/4goyy37

Prince Caspian
Prince Caspian's strongest scene was Aslan at the river, in the end. The lighting in that scene was very well done: even Andrew Adamson said so in the audio-commentary. The moment when Lucy and Aslan talk in the wood (just before Aslan wakes the trees) is also quite well-done. The rest of the movie, was a step back from what I had seen. While still very nicely animated, they just added too many mane, or they were simply too overwhelming. This shot demonstrates that quite clearly: http://tinyurl.com/6jeh7j6 This was mostly noticeable in the straight-on shots of Aslan's face. A thing I liked was that Aslan actually got bigger in Prince Caspian Overall, I liked quite a few of Aslan's shots in PC, but not all of them.

The Voyage of the Dawn Treader
Now we get to good ol' VDT! When I first saw the very first trailer, I was shocked to see this shot in it: http://tinyurl.com/4q2o2wu My first reaction? "Aslan looks like a puppet!" Looking back at that, I'm actually surprised by that reaction: a CGI Aslan actually looked like a real-life object?! Now that's cool! Aslan seemed to have gotten bigger in VDT once again Other than that, the problem with the mane from Prince Caspian seemed to have gone away. As in PC, VDT had a scene with amazing lighting for Aslan: http://tinyurl.com/4jl86vv I love that shot a lot! The scene where Aslan delivers his famous lines at the end of the movie looks interesting: http://tinyurl.com/4k5q73n It think it's the closest shot of Aslan's face we have seen before (which I think is nice, as it adds to the very personal lines he delivers). While the feeling of a realistic lion isn't fully there for me, the feeling of it actually being there physically is greater than any other scene I've seen in the Chronicles so far. You could actually run up to him and give him a big hug! Loved Aslan's CGI in VDT!

Now that I've critiqued the CGI for the three films, I'll say that I liked them in this order:
1. VDT
2. LWW
3. PC

There. Now I also want to say that I very much appreciate all the effort that goes into creating Aslan. It's a tremendous amount of work, and I am very much amazed by what they're able to do with it. Despite those few flaws, Aslan's CGI is still a fantastic achievement!

As for the Aslan images that have appeared on all the Narnia posters to date, I don't think they originate from Aslan's 3D model. I think they're either real (touched-up) photos of actual lions, or, in the case of "Snowy Aslan", some amazing artwork by some amazing artist(s).

On a side note: why did they use the stand-in puppets for Aslan and the badger on the back of the Blu-Ray/DVD packaging for Prince Caspian? The Badger looks very much like a puppet, and Lucy is hugging Aslan without the mane that were added with CGI later. Just something that annoyed me, but it's not a big deal

Definitely LWW for me. LWW Aslan was the only movie where the animation looked so realistic in places that I actually backed up my DVD to watch it because it looked so real. (The first was when Aslan meets the Pevensies, the second is after he finishes talking to Edmund and jumps down off of a rock.)

I definitely voted VDT, LWW, PC

I voted PC, 2. LWW, 3. VDT
because I thought that in LWW and PC Aslan looks mane-ly like a real lion (Sorry, couldn't resist) and his appearence is consistant. However in VDT Aslan looks very different. He has a wider nose and a slightly more animated face and there was something about his mouth when he talked that slightly irritated me, but I can't remember what.
But it wasn't bad CGI over all and there wasn't really much between them

I just watched LWW yesterday, and I have to say that Aslan is the BEST there. PC was...ok. It had it's flaws and all, but overall he looked the same. In VDT, Aslan looked horrible. His eyes were a strange yellow color and he looked like a toy Lion. He lacked emotion and feeling

The CGI for Aslan started good and has gotten progressively worse in each subsequent film. The same goes for his character treatment.

For me LWW was the best, PC was pretty good, and VDT was Meh.

LWW was the best, i know that in PC Aslan was older, but he just looked so weird and different in PC than any of the other movies.

I always felt that the LWW version of Aslan was the real lion. Obviously, we know it's just a computer generated image, but for the moments Aslan is on screen, I can completely believe that he is a real lion. It all comes down to the painstaking details. The layers of color give his fur and mane a sense of believability. The sense of weight has also been given strenuous attention. For example, as fantasia_kitty has mentioned, when Aslan bounds off the rock after talking to Edmund, the sense of weight is so believable. I still get chills when Aslan walks out of his tent for the first time. Looking into Aslan's eyes, there is a real since of soul and emotion behind them and that ties the audience with the character (if it's not there, the character is not successful). Aslan actually had three models for LWW (his first scenes, at the Stone Table, and a "golden" model used for after his resurrection). The crew at Rhythm and Hues definitely did their homework and their hard work certainly paid off. I truly felt that they understood the character of Aslan (which is key).

As for PC, Aslan was, ultimately, a step down from LWW. Granted, some of his movements and actions were a bit more believable than in LWW. Aslan was a "real" lion in the scene where he speaks to Lucy, and my favorite, at the end of the film when he speaks with Susan and Peter. At other times, mainly facial expressions, I just cringed. I can't even watch when Aslan and Lucy walk up to Beruna Bridge, I'm completely drawn out of the film. His roar here is amazing, but everything else still feels in the preliminary stages (lighting, animation, etc.). Aslan also felt really unproportoinal in PC. I do like the fact that he became "bigger" from LWW, but it also felt like he put on a few pounds (as if his legs were a bit too stubby to hold his weight). This didn't appear in all the scenes, but it was enough to be a distraction.

I can't say anything for VDT yet because I've only seen what was in the trailers (and that's not an accurate representation of the final).

LWW was good except for an occasional shot (I can't think of specifics, though). In PC, Aslan looked kinda fakey at points, particular in Lucy's dream, but overall it never through me out of the movie. I don't actually recall seeing Aslan in VODT, though I did hear his voice when he roared at Lucy for trying to read the beauty spell when she was supposed to be looking for the uninvisible spell. If we're going to include the TalkingLionHead which loves to give trite advice and 'wisdom', such as in the scene where Lucy reads the beauty spell and at the end of the world, the CGI was probably on par with PC, but worse enough that I would put it in third place.

I think that LWW had the best Aslan. PC wasn't very good VDT better then PC, not as good as LWW