The USN Sevastopol goes up to 42, making it faster than the Maryland. Sorry.
The penalty for having a ship well below the crew is also largely negated if you're good because the EXP bonus for hitting BB4+ is far greater than the penalty (still only a 10% reduction 24 levels above ship, and Iowa is 28). The Maryland only gets that bonus on BB5+, so in some cases results in less experience for the same damage.
OTOH, the Maryland is fun and hits very, very hard, something the Seva can only dream of. If you can get both, get both. They're both go-to leveling ships for the USN, but they're different and neither is that much superior. Using regular tree ships is more a question of wanting to experience them and personal taste - USN BB1-3 aren't so hot at level, but great fun with high level crews.