I chose Constitution, but it totally depends on what era I'm living in.
If it's 2250-2290 I choose Constitution.
If it's 2290-2360 I choose Excelsior.
If it's 2360-2370 I choose Galaxy.
If it's 2370-2387 I choose Sovereign.
In the 2260 of the JJverse, I pick Dreadnaught/Vengeance Class.