Here are some in hand comparison pics from another thread (I'm sorry I don't remember who's these belong to)
I got the SS one when it first came out, and I must say I have always loved it. The only thing I really didn't like about it from the get go was the over-sized lightsaber. I don't use the "lit" one for that reason, but it doesn't matter. I do love the hands/gloves of this figure they are so expressive and the poses I put my Vader in takes advantage of that.
I'm also partial to the ESB/ROTJ look, so I thought HT ANH Vader would be an easy pass for me; which is good because I'm getting almost every other OT HT figure and I don't want to spend more on Vader if I don't have too. However there are a few things putting me up on the fence to consider HT Vader now.
I first started looking at it more seriously after I got my Ben Kenobi. I thought the LED light up sabers was going to be a gimmick I wouldn't care about and I wouldn't use it, but after having Kenobi's in hand I have to say it is fantastic!!! So the HT Vader's light up Saber should get some points if you are making a pro's and con's list in my mind.
The second thing that makes me consider the HT Vader is the helmet. I have never been an ANH Vader guy, but I also never really paid attention to the differences in the helmet. I always attributed my preference for ESB Vader as a preference for him wearing the robes under the armor instead of over and the armor itself being more polished and having a clip to keep the chain from disappearing under the neck of the mask. BUT, after looking more closely recently I think the initial dimensions of the ANH mask is actually far more menacing. The biggest reason for this I think is the more pointed widows peak on the helmet, but there are some other factors too. The Hot Toys Vader captures everything good about the ANH Vader mask. I also like that it seems fuller, and when it is side by side with the SS one the SS one's dome looks too narrow. The HT ANH Mask simply wins. The only thing I am not really sure about is the "battle damage" and intentional paint scratches on the grill. It's accurate to the movie, but it's also something we only notice now because of being able to watch Star Wars in HD and blueray. I may have preferred they didn't include this "detail" on this scale of a figure because I feel like I might notice it more on the figure than we do when watching Vader in ANH.
After that things get a bit closer. I think the body Suit of the HT figure is better, but I never hated the SS one. The hands/gloves of the HT one though still bother me. I am not going to want to pose him in a way the draws attention to the hands in the same way I have my SS Vader posed with his right hand out in some expressive gesture. Those pieces of "glove" that fit over the back of the sculpted hand of the HT figure looks like a Halloween costume that some mom put together because she couldn't find gloves with long gauntlets.
Finally, the last difference I think that might matter to people is the difference in height. The SS one is taller, but most people seem to think the HT height is more accurate; he certainly is tall enough. Some people are bothered by SS height saying it looks too tall. I've always been fine with it myself. The height difference isn't going to make me like one over the other, but it's important to some people so they should know about it so if its important to them they can get the one they prefer.
The other differences are not very significant to me. I don't care about the breathing or talking. I do really like the SS light up stand and I think the separate helmet display showing how the separate mask and dome are cool. I'm keeping these accessories even if I decide to sell my SS Vader someday. The HT stand though has the advantage of matching all the other HT SW stands and the droid looks cool.
I think both Vader's have their strengths and weaknesses and for me it may come down to how you want to pose him. If you want to pose him in a way that takes advantage of gestures to show expression with his hands as if he is force choking someone, telling them he is there to get them "back on schedule" or revealing that he is actually your father, then I would go with the SS one. But, if you want him with his lightsaber on go with the HT one. I might even say this even if you don't care that the HT one lights up, because the SS one really is way too big and looks terrible (especially if you have other figures with more in scale lightsabers near by).
I haven't decided to get the HT figure yet. I am still on the fence, but if I do I think the ideal pose for the HT figure is the classic 1977 promo pic
