byzantines have a good unit roster. they are a good faction if you enjoy horse archer armies but cant stomach playing as a muslim.

russias units are so-so but they are a fun faction to play with because they are a bit more challenging than most.

the towns/cities in their "sphere of influence" are all extremely undeveloped at the beggining, it takes ages to expand becasue of the distances and lack of roads, and of course they miss out on the crusades.