Hi all.
This is something I've been thinking about alot lately.  I've been playing about a year now.  I've tried most of the planes in the lineup, although I've definately flown some more than others.  Still, I think I've given most of the lineup a fair try.
Now that I've been playing a while, and beat most of the total NooBiness out of myself, I think I've developed some of my own style of playing the game.  I have my own way of approaching fights and conducting a dogfight.  
Additionally, I've come to feel that certain planes just inherently seem to 'fit' my way of playing better than others.  What I mean is this:  I can up most almost any fighter in the game and land some kills.  But, there are some planes that I find much more success with than others.
For example:  I have really, really tried to like the jug.  My squad, the 348th FG was a P-47 squad in WW2 and so for history sake I've tried to fly and be proficient in the plane.  But, I simply cannot adapt myself well to the style the plane demands.  I have an idea of how the fly the plane, and I have great squad mates who are proficient in the plane and can coach me through a successful sortie, but I don't 'enjoy' the flight, and I don't feel comfortable in the plane.
However, a plane I find an absolute joy to fly is the Ki-84.  I put this plane on and I feel like I can...just fly...without having to manage my style so much like I do in the jug.  I spend less time thinking about what I'm doing and I'm flying more instinctively.  
Furthermore, I simply stink in 50 cal planes.  Try as much as I want, I just don't enjoy success in the pony.  I can get assists all day, but I have real trouble keeping those guns on an opponent long enough to get the kill.  Cannons are my friend.  I probably have more air-air kills, and a better K/D in the Mossie than the P-51.  
Anyway, I think that there's a few way to approach this game.  The really good players are going to land kills in anything.  Heck, I saw SHawk land a few kills in a C-47 the other day!  But I think for those of us that are sort of middle ground, there may be a struggle between either adapting how you fly to a plane, or picking a plane that simply suits your style.  For me, I think I'm finding alot more success by finding the planes that just fit how I like to play best.  
I'm interested to hear how you guys feel about this.