Gazoinks: I basically divide the TW games into two tiers: Map and Battles. My favorite battles are:
-Medieval 2
-Shogun 2
-Rome
-Empire
-Napoleon
Whereas my favorite maps are:
-Empire
-Medieval 2
-Rome
-Shogun 2
-Napoleon
So Medieval 2 is the most well-balanced for me, but I can spend more time with Empire thanks to the scope. And, in case you can't tell, I found Napoleon pretty lame. >.>
Personally I'd put Rome further down the map list on account of how unbalanced it was in a long campaign. Distance to Capital was a factor that could turn a civilised city into a bunch of mad, rioting bastards who'd never surrender no matter how many thousands you kill. It just didn't make sense.
Equally I'd switch it with Medieval 2 for battles due to the more interesting unit types available.