Go for the 75, don't upgrade filtration, just add to it.
If using a HOB get a secondary, or even a third this way when it comes time to clean, you can do one at a time, and always have 2 established filters running.
Finally broke down my 20 long, moved it's residents into either a 15 rimless, and 55 community tank.
Considering dropping another tank or two within the next month, just to keep maintenance down.
Also would allow me to have much better filtration on the remaining tanks, since I'd have extra filters haha.
Random side question, Do any of you Michiganders run Marina slimline filters?
I've been considering buying a few since they're cheap but I'm curious to see if they're worth it, or if I should just buy some small marineland or aquaclears instead.