i too started with the 2005 reboot, i started last month actually. now in season 5, which i believe was considered a mini-reboot with new writers and whatnot. took me several episodes before i started to think i was enjoying the series, the quality of the costumes and cgi was certainly amusing during the first couple seasons.
several episodes made me think the series was a mini-horror/suspense thing, especially the empty child episode lol
why cant they just stay with one doctor
I'm pretty sure they've had more doctors than popes
Because the actors want to move on. In fact, The Doctor was supposed to be Hartnell but since the show got so popular, they couldn't just end it. So the writers then had to create a plot device to keep the story going.
i kind of like it too. getting attached to various actors is saddening when the next doctor comes along, but it's an interesting aspect of keeping the character alive and fresh
David Tennant could have stayed forever. That would have been ok.
personally (though i've only watched the newer ones), i liked christopher and am enjoying matt, but david just seemed so much more entertaining and fun. i really didn't want him to go :(