Depends on your budget, skill level, and amount of interest.
FT has many trainer type speed build kits which will be much cheaper than a tundra or timber. Cheap is good if you aren't an experienced pilot, as you have a higher likely hood of crashing.
I've never actually flown a tundra or timber, but they seem to be highly successful models, so if you're able to fly already I'd say you can go wrong with either one.