I like them both, but I prefer Tennant overall. This is partially because of the new direction DW has taken with Moffat though. Since Matt started with Moffat, it’s kind of hard to separate his Doctor from the series in general, and I really preferred RTD’s DW to Moffat’s. However Matt really is a terrific actor. I thought he really showed how good he is in A Good Man Goes to War and in the Rebel Flesh episode (I can’t remember if it was the first of the two-parter or the second!) where he gets angry and kind of attacks Amy.
I think one of the main things that detracts me from Matt is how ‘hipster’ his Doctor is. It’s like Moffat is trying to cater only to the teenager blogging crowd and although I guess I identify with that, it’s not really appealing to me in the Doctor. It just needs to be toned down a bit, in my opinion.
Anyway, Tennant just went above and beyond with every single episode of DW, including the ones I don’t like. When I watch him, I believe that the show is real and that the Doctor actually is out there frolicking about.