Spits are a terrific plane, I quite like the spit IX.
K4 is also a great plane, and its quite easy to die in if you fly like me. If you bnz with it, you will live, its fast and can out run darn near everything. K4 IMO is one of the trickiest birds to master, but when it is mastered, its hard to beat.
Who am I kidding, I like to fly all the planes, they're all so much fun. Why would anyone stick to just a select few?