Very early on in this thread someone pointed out that the Sovereign is a smaller class, isn't also a better war vessel though?
Hard to tell. The Galaxy
class scored victories in the Dominion War, and (rather curiously) was the only starship to ever actually destroy a Dominion vessel larger than the tiny battlebugs on screen. The Sovereign
class was nowhere to be seen.
...after the Transwarp drive was deemed a failure
This is rather difficult to believe, considering that after these movies, Starfleet is suddenly seen using a warp drive that looks very different: big flashes at warp entry, streaking stars when the ships move, a new definition of Warp 10. Surely something
new was a great success - and transwarp is a natural candidate.
The success or failure of transwarp shouldn't affect Sulu's getting command of NCC-2000 much either way...