My favourite manufacturer has to be Tamiya, although I've only built 2 kits from other manufacturers. One was a Hasegawa Evo V WRC but I made a balls up of that one. Good kit though, and the photoetched parts are being recycled into my Pug 206 (Tamiya
).
The other one was a Revell Corvette C5-R which has great engine detail but absolutely awful fit problems. It's on the shelf waiting to be finished and it will probably stay there for some time.
Favourite subjects are WRC and street cars, but I've got a Calsonic R34 lined up for a bit of a change.