We're a pair of retired, quiet people who don't value ostentation and definitely devalue pretention. Casual is what we like and what we look for. Having said that, I'll now say that I prefer Princess over Carnival. I like Carnival, and we've cruised several times on Carnival. Our first cruise was on Carnival. But Princess just pleases me more. More quiet people than rowdy people.
Dress standards on Princess have relaxed over the years to the point that I've told hubby first that a full suit was no longer required for formal nights, only a shirt and tie, then recently I've told him that only a dress shirt and decent slacks are required. No tie needed. This isn't a problem with dining room staff. Funny thing is that on our cruise this April he forgot his dress slacks and went into the dining room on formal night in a nice pair of jeans and a dress shirt, top two buttons unbuttoned. No problems with that. He's a very happy camper these days.
On Princess, there's also the bed thing. Those beds are wonderful!