I can't compare Oceania to Regent as we haven't sailed Regent, but I can give you my Oceania review. We did a Caribbean holiday cruise, rt Miami, in Dec 2019 (our last big trip before quarantine). First time on Oceania, on Riviera (one of the 1100 passenger ships) for 10 days, I think. (Later, I will look to see if I reviewed this trip here or on cruise critic ;-) Another caveat - I don't enjoy beaches, don't love to cruise the Caribbean, but my inlaws wanted us to do this trip with them, so of course!

The ship had more people than I enjoy, but I did enjoy the amenities the larger ship offered - more restaurants and bars, cooking school - we did 3 cooking classes!- art studio etc. We had a standard balcony, but I think it was the second or third tier up bc it was nicely positioned midship. Though the space was fine, we much preferred our seabourn cabin - better layout and more efficient use of space. I'll have to look up the cabin size but I think ours were quite close on each cruise.

The food is amazing. I prefer seabourn and can't wait to sail them again but oh my the food on Oceania really is that good. But also my very meat & potatoes inlaws love the food too. They've done several Oceania cruises in the past 10 years and had planned to do another this year but had to cancel due to health concerns :-(. They have a strange way of making Old Fashioneds, but they'll make it like I like if I tell them....(we had a drinks package and tips came with our travel agent and a deal the cruise line was running; we did our own air - always do- and our own excursions as well)

I'll go see if I wrote a review anywhere to share....