I usually search google for reviews on kits before I get them. I just type the name (eg. Tamiya F-51D 1:72) and 'review'. Usually comes up with something, atleast for the more popular subjects.
From reviews I've read so far, Trumpeter kits seem to be well fitting, but a little 'over detailed' (in 1:72 atleast) - but then as someone once said in a review, any scribed line in a 1:72 kit is already out of scale...
Dragon kits are usually pretty good, but sometimes bad fitting. Often there are certain detail inaccuracies too. This I know from experience. The good thing is they sometimes come with engines (1:72 Ta 152, Do 335, He 162, Ho IX, for example)