Like I posted in response to the Jacob and Bella couple win, I'm Team Jacob because of his unconditional love for Bella. He's so loyal to her and cares deeply for her, where he's willing to sacrifice everything just to protect her. Not only from harm of others, but from herself. He's light, she can be herself and so happy around him without feeling like he won't understand. He's sort of a carefree escape for her, a best friend, someone she can be open and honest with. Taylor and Kristen have a similar friendship, and it shows through on screen in their characters. Kristen even said in the DVD extra (Becoming Jacob) that she loves Taylor and its great coming to work and believe everything someone says and not have to lie or change. With Edward, its always so intense. Their conversations always turn so rigid. She glares at him in amazement and awe, and always wants to be changed by him, which seems like a phase. I believe love should be with someone who you can be yourself with, laugh, tell your secrets, and not feel like you have to pull teeth to make them happy. Jacob is that. He would give up everything just for her. Don't get me wrong, I know Edward would too. He almost killed himself because he thought Bella died, but I feel like Bella's love for Edward is more lustful than pure. Bella's love for Jake is just that, and although we know the outcome, if situations were changed and she didn't have to change because of the Volturi, I feel she would have picked Jacob. She wouldn't have to change for him and lose the life she has. He loves her no matter who she is. He loves her even after she's had Renesmee and he will always for eternity. It all boils down to this. Whether they changed Taylor and gave the part to someone else to play Jacob, I would feel the same. Its the story that makes me love them so much. I liked Jacob from Twilight, liked him in New Moon, and will like him in Eclipse and Breaking Dawn. I think he's the better person for Bella. He definitely stands as the ultimate man for her in my book. No loss, just gain. She's lost so much with Edward.
I do understand where you are coming from, though. It does help that Taylor and Jacob (pre-transformation) have similarities also. Taylor just happens to be extremely good looking (don't get me wrong, so is Rob), but he's also an extremely grounded, great guy. He's perfect for the role and I think no one else could have portrayed Jacob better than him. Who else puts in so much effort for a role? I respect him and his drive.