I agree that giving the players the option of “banking” a portion their bid is important. Usually units pre-placed on the board are better than extra money in the bank, but there are obvious exceptions, such as the $1 to Japan allowing an IC and two trannies to be purchased round one.
I don’t think there is a consensus “best bid” on the War Club for that standard $9. Common options include:
3 Inf (either all for Germ or 2 Germ, one Jap). If a Jap Inf is used, it usually goes to Frindo. Extra Germ Inf may be in Europe or Africa, or split between them.
Tank and Inf in Africa for Germ, $1 to Jap.
Trannie for Germ, $1 to Jap
Many others I’m sure.