I think it's fair to say that He is my Favorite, the reason I started watching DW, then I went back and watched the rest.
When I look at other Doctors, they don't compare the passion that Tennant brought to the screen. In his last scene at the end of "The End of Time" I literally cried with him.
He had a way of keeping me interested in the episode and made me feel that at any moment a Time Lord would park his TARDIS outside my house to take me away to travel in Time and Space.
I doubt that any other actor will portray the Doctor the way Tennant did, but I could be wrong.
I feel the same way. He's amazing and irreplaceable. I know there are those who don't like MS but I can't not like him; I kinda feel bad for anyone who had to follow in DT's footsteps...