5 Olympic-class
4 Parliament-class
3 Centaur-class
2 D’Deridex-class Romulan Warbird
1 TOS Romulan Bird-of-Prey (the updated version seen in PIC and SNW is also great)
I also want to give an honourable mention to the Niagara-class, which is a three nacelle abomination. When I started running my Star Trek Adventures game, I choose the Niagara-class because I wanted something relatively unique which still that communicated to the players they weren’t in a top of the line, prestigious ship. It’s been just over two years since we started playing the adventures of the USS Dauntless (yes, I know, but it’s not that Dauntless), and the ship has really grown on me.