One of the most common what-ifs is the Type 82 fitted with Type 988 'Broomstick' radar. Oddly when the Type 988 was still on the design there were no aft funnels and there were a few other structural changes, mine is a amalgamation of both to better reflect what HMS Bristol might have looked like.
As a footnote, the Type 82 seems to be one of the most kitbashed of the earlier Shipbucket ships. I'm sure we are going to see a lot more...