I know it's just personal opinion, but...
As someone who consistently
plays the game in 1st person (only switching to 3rd to admire my character and do screenshots), I much prefer the 3rd person finishers. The 1st person ones look really awkward, while the 3rd person ones (complete with slow-mo and blur) make my character look all badass and epic. Great stuff. If we had to be stuck with only one type of finishers (1st OR 3rd), I'd vote for just 3rd every single time.
Just goes to show how different opinions can be.

edit: can't give feedback on horse riding or werewolf. I don't do either. I do wonder what the die-hard 1st person folks think of all the other 3rd person parts - like crafting, mining, sitting in chairs (which I remember also being like that in Oblivion. Don't remember if sitting down was 3rd person in Morrowind.)