Because I'm quite frugal player, I am satisfied with normal skirmish, especially in normal multiplayer game it is usual option.
Other game modes are more or less for fun, but for example both "time conquering" modes are quite interesting for player who has problem with BFME1 strategy (which is primarily about conquering) and these modes are perfect workout for him, because he is under pressure and simply has to expand his territory.
Overall number one is for me normal skirmish, number two legendary heroes.
Heroes cost are under or around 3 000, so that heroes are weaker than in previous version. And legendary mode is great compensation, just sometimes are heroes "too legendary."