I like early and the beginning of Mid era. The start of the arms race. Each race has their own strength and their own weakness; their own flavor.
IMHO, by the end of late, the arms race has left all the base ships in a stalemate, just different torps (ever do a phaser count on the BCHs?), and all the real power lies in the ships with the expedibles (PFTs, CVAs & drone fleets). Early is about flying your ship better than the other guy, knowing how to cover your weakness while exploiting his; while late is (by comparison) about bringing more and better ordinance to the front.
Honestly, I think that's something I very much liked about AF, the slow passage of time. It didn't rush you through the ever changing times of early & mid to the static period of late era. Yes, those 1st terrible years for us Rommies drew out like a knife, but it made the Golden Years of the KRC last that much longer and taste that much sweeter. On the servers since then, all that drama would be done and over in the 1st 4 days of a month long server, if not skipped all together.