The La5 is the best plane for defense. The 190A5 is the best plane for bomber intercepting. The 109G6 is better for fighter intercepting. The yaks and La5 are clearly better for short distance defense and lower alt fighting. The 109G6 out turns both the yaks and P39 and turns almost exactly the same as the La5. The La5 is a bit easier to fly than the G6. Overall, I think it's a fair fight all around. Now if the Russians are attacking and not defending, the 109s and 190s will have a much better advantage. The small gun loadouts are detrimental when having to fly far distances. You get there, make 3 or 4 passes, and if you don't watch out, you will run outa ammo and have to fly all the way back home. It's not very much fun, also, they have a lot less gas than the German planes. I prolly wouldn't fly a Yak7 if my life depended on it. The yak-9u is decent. The la5 will be the most successful plane on the Russian side. The P39 is going to be very hard to be successful in, probably the hardest plane to fly of the set. The 109G6s and 190a5s will fair fine. I think the La5 is the most versatile of all the planes and will be the most deadly in the right hands.
Pipz, the reason is that, the La5 is a defense plane with quick capabilities. The 190A5 is a BnZ plane best used for attacking lower cons. You prolly die more in the La5 because you are lower, more aggressive, and this creates opportunities to get picked easier.