I haven't conpared the differences but it feels like the generals add 5-8% of winning battles so the problem for me is they are just too damn expensive, if I'm engaged in 2 50% battles I'm actually less likely to use a general because it typically means less is at stake. If they gained experience that might help but really I think they just need to be better and cheaper.
Regarding the other cards I've found some of the strategy cards to be very powerful (250% gold production for 2 turns, -100% gold production on an enemy tile, 75% cost reduction on air units for one factory for one turn) but the Wizard Tower and Academy do consistently throw out cards that have only marginal utility at best.
