Steven,
As a general start, AH has posted on their web site speed and rate of climb figures for most of the airplanes. Look under the HELP/GAME OVERVIEW link and look under the Planes,Vehicles, Boats link.
This should give you an easy starting point comparison of which planes are fast and which have the advantage in climb at various altitudes. Other factors such as best turn rate, ability to take damage, energy retention, acceleration, roll rate, high speed handling, weapons etc., are not as easy to find but they're out there.
A really good suggestion is to fly as many different airplanes as you can (maybe in the training arena if need be) to get a feel for each airplanes strengths and weaknesses. I'd say stick only to 2-3 different ones in a single tour. Also, fly the bombers a bit too to learn their weak points regarding guns and angle of fire.
[This message has been edited by SpitLead (edited 04-30-2001).]