I liked the Enterprise-A bridge from the end of The Voyage Home
I think my favorite variant of it was the one from ST VI. It just looked more realistic.
Out-of-universe - i.e. for filming purposes - I'm sure it was always the same set, but IN universe, I am guessing that all three were separate replaceable modules. They just look too different. If Starfleet's going to go through that much work to alter a bridge, surely it'd be easier just to start over?