We've gone on Carnival 3x, RCI twice, and Princess once. The reason we chose Grand Princess over Carnival Destiny class ship was the GP was about a thousand LESS for the same cruise with a comparable cabin. Same reason for Destiny/Spirit class ship vs RCI Explorer. Explorer won out with being close to a thousand LESS. I thought the Grand was superb, Explorer had everything, but Carnival's food and presentation of the food was better than either of these. Otherwise they all seem comparable in experience. HOWEVER, there were a couple young girls on the same floor as us on the Grand that smoked pot, we even heard a couple cabin stewards joking about it once, smell was VERY obvious, yet nothing happened to these two. On EOS, a few drunks were tossed off at different ports, one was a group of 50-60 somethings that started a fight on the Royal Promenade. On any of the 3 Carnival cruises we've done, we don't know of any incidents, and security seemed tight.
How people can say Carnival is cheap when other cruises are SO much less is beyond me. As for the reputation, testiment to human nature that it can stick yet no longer true. As for deck space, I'm not a sunbird, I appreciate shade with my very light skin, so I have no clue what the chair situation around the pools is like on others. On the Grand, I enjoyed swimming at night, the pools are amazing on her. Explorer adult pool has sprinklers, that's not for me. Decks on all the ships I've been on have seemed pretty packed with sunbathers. My experience is Princess seems to handle crowd control best.