First of all, given equal pilots every plane has some that can beat it and others that it owns but some have more of one than the other.
Before choosing a plane you have to know what style of fighting you like. Are you a boom 'n' zoomer or a turn 'n' burner? Do you prefer to hover above the crowd seeking opportunistic kills or do you prefer to dive in and mix it up? Do you fit somewhere in between or is it just too early to know yet?
Even once you have that figured out your mission plan may dictate a different choice of plane. You probably wouldn't want to take a pure fighter to attack a base. You probably would want something with high altitude performance if you were going to escort high alt bombers. You wouldn't want a pure b'n'zer in a turn fight and vice-versa.
For these reasons many choose a "mid-tier" plane to begin with. One that plays well in several roles. There are several among that category, probably a third of the plane set.
I suggest you go to
http://trainers.hitechcreations.com and from there follow the links at the bottom of the left navigation bar to Soda's aircraft evaluation pages then to Doc Gonzo's performance stats site to find something that looks of interest to you and go try it.
If it's not what you expected then repeat the proccess until you find something you're comfotable in, then stick with it for a while.
This is going to take a little bit of reading and research on your part but it will pay dividends as you'll remember some of what you read when you meet an opponent and you'll at least have some idea of what his plane is capable of. When you meet an opponent make a mental note of what he was flying. Win or lose go back to those web-sites and re-read the information of those planes to see where you might have gone wrong or what you might have done right.
The way to win is to know what your own planes strengths and weaknesses are and your opponents, then expoit your strengths against his weaknesses. Until you get to that point you will be pawned continouously.
Good luck and have fun on your journey.