We a
Started with 75 which was a nice size except I wanted tangs. So we got a 120 and still not enough room for tangs, then upgraded to 300 6’. I wanted bigger fish so also got a 300, 8’ for larger tangs and angles. We still have a 75gal which has been taken down and restarted and is now mostly coral instead of fish. So I would say it depends on what you want to keep (coral, fish, large fish, or both) space, money, and time. 120 Worked the best I feel of all our tanks. Not too big not too small. Sometimes wished we would have been satisfied with that instead of wanting more. Good luck and choose the best for you’re lifestyle and desires for fish/coral.