Here are a few aircraft which have certain advantages for a new WarBirds pilot. I'll list their disadvantages as well.
I would go for the Spitfire Mk.V everytime. See what the guys have to say below about it, but I think the main reasons are its turning ability, and its firepower. It is also available for a large portion of the Rolling Plane Set (RPS). Its only real shortcoming is its limited ammo supply, and a lack of speed against aircraft like the Fw-190 and P-51 Mustang. You might not be able to catch them, but they don't have a hope of turning with you.
The Spits have a lot to recommend them. They handle pretty well at all speeds, from right above stall to 400+ mph. They turn very well, which is important for a newbie. Turn fighting is what everyone thinks of when they think of WWII combat. Dogfighting, twisting, turning, trying to get the advantage in fast and furious combat! That's what the majority of new pilots are going to try, and the Spit is in its element right there.
Good visibility, great hitting power, great turning ability, and a pretty good acceleration in a dive or flat. Plus, they are very docile on takeoff and (every newbies dream) landing.
The P-38L is also a good choice because of its lack of engine torque troubles, its fine handling, and its nose-mounted armament (which does away with convergence hassles).
The F6F Hellcat is a great choice - maneuverable and holds energy well - its great drawback is the lack of a rear view.
The Ki-84 is a good plane - fast, manueverable, awesome power, and good armament. It suffers a bit at altitude.
The Zero handles wonderfully (at low speed) but has a lack of speed, and is made of rice paper.
The Ki-43 is one of the finest Turn and Burn planes in WarBirds to fly, with fantastic manueverability, and a reasonable turn of speed. But its two pop-guns are not going to get you many kills.
The Yaks, especially the Yak-3, are fine choices.The best view in WarBirds, no convergence hassles, and no handling vices. Add the Yak-3's manueverability, accelaration, and a reasonable turn of speed. The ammo clip is a bit small, and it has a lighter punch than aircraft like the Spitfire.
All of the Luftwaffe planes are fairly difficult to learn for new pilots - if you're a Luftwaffe nut, try starting in the Bf 109E or F.
Well, all the varients of the Spitfire (except perhaps the XIV) fly similarly, and taking RPS considerations into account, some version is available for the entire RPS. It, along with the P-38's, is a good starter plane.
German planes are generally considered more "advanced" level. The Fw 190's are fast but difficult to handle, while the Bf-109's, while they maneuver and fly more smoothly, suffer a bit in the open arena. While the Bf 109 is one of the best planes early in the RPS, it fades quickly. Because some people doubt its competitiveness, and its overall low firepower, it's better left to more experienced pilots. The Bf 109E and Bf 109F are the most competitive planes in relation to their place in the RPS. The Bf 109G less so. The Bf 109K is powerful and fast, but is hard to handle and has a tiny load of main ammunition.
The Corsair is a powerful plane, but can be difficult to handle. Getting it into a bad spin is something you don't want to do.
Generally most players recommend the Spit or P-38 as "first planes".
I might also add the Yak-9. If you can handle the low ammunition load, it's an decent aircraft with no surprise handling characteristics.