So essentially there are three fundamental schools of thought. The first is to go full Sealion then Barbarossa as Sealion takes away about 30 Ipcs from the Allies while adding 8 to the Axis and helping Italy in Africa, hurting the Allies up front though but while giving the Axis little reward until later. The second school of thought is completely Barbarossa first as it takes away a few Ipcs per turn from the Allies giving to the Axis, while taking away more Ipcs and earning more but over a long period of time. The third school of thought is to simultaneously do both while staving off one slightly until the other is dealt with, getting more done but with both operations taking longer. What do you guys think?
Your math is off. Yes, you gain about 30 IPCs from the UK, plus the per turn income from the London/Scotland pieces. However, you lose whatever IPCs you spent on transports, plus whatever IPCs you “spent” on casualties (especially those to your air force, which are very hard to replace). That’s typically on the order of 70 IPCs, giving Russia about 20 more ground units than you have (and that’s before you start trying to replace your air force).
It is true that losing the UK creates an unbalanced situation for the Allies. However, I’ve never had an issue recovering as the Allies.
The only time I ever did Sea Lion my opponent left the UK so weak that I did not have to build transports at all. It only cost me about 30 IPCs after the seizure of money and my losses. I have, however, intentionally encouraged an early Sea Lion from my opponent because it is a losing move on the part of the German player. So much is spent on transports that Germany cannot effectively push against Russia.
A late Sea Lion, which the UK player must AlWAYS defend against, is a much more effective strategy for the Axis. Late in the game, the UK is often laser-focused on the Middle East and occasionally forgets about the UK defenses. The balance of powers after Moscow is fully turtled, the Middle East is highly contested, and India has fallen is much more delicate than it is on G3. Losing the UK at that point is devastating for the Allies (as in, they lose outright).