Definitely branch out and try all the cruise lines. I think that people are missing out if they don't try everything. We've done a lot of cruising and have figured out what "fits our style" the best, so to speak, but that said, in the past year we've been on
DCL, Princess, Virgin Voyages, HAL, Carnival, and RCCL. They all have their pros and cons:
DCL: Our favorite, but definitely can hurt the pocketbook!
Virgin: Virgin may be our "new" favorite. The food is amazing (no MDR, it's all "specialty" and it's all included - also, there is no buffet, it's a made to order food court), all tipping is included in the fare (no adding 18% on to a doing price), free candy, gelato ice cream, the list goes on. It is all adult though, and it's a bit different, so there's that, but we love it. Also, the Duel Reality show is amazing.
RCCL: Actually, probably our least favorite, but then again, we don't use the things that people love about it (we don't zip-line, or rock climb, or ice skate, etc.) and we don't have any status with RCCL, so we don't get any "perks". I am not a fan of the included food options (no poolside grill! why??? I don't want to have to go to the Windjammer for a burger), however, if you spring for the Ultimate Dining Package, I think it would be a lot better. All that said, we enjoyed Oasis more than we did Independence or Serenade. Also, and this is specific to the Oasis, CATS needs to be put out of it's misery... Loved the Aqua80 show though!
Carnival: This may not be a popular opinion here, but we enjoyed the Carnival Mardi Gras way more than we did the Oasis of the Seas. The new Carnival ships (Mardi Gras, Celebration) are amazing. Not sure I'd jump at their other ships, but these two are great. There are a lot more included food options (Shaq's Big Chicken is legit!) and I think their "comfort food" quality is much better. Guy's Burgers and the BBQ place are complimentary on Mardi Gras, for instance where they are an upcharge (Johnny Rocket's/Dockside BBQ) on Oasis. There are also a ton more included food options. We loved that on Mardi Gras the Cucina del Capitano is included. Ate there 3 nights. And if you want the bells and whistles, there's a waterpark, ropes courses, and a roller coaster on the ship...
HAL: Definitely an older crowd, but the food is good and consistent and DW loved all of the live music options that they had all over the ship.
Princess: I will admit, outside of DCL, Princess is our "go-to" line. When I try to explain it to people I always say that Princess is like that old sweater that just fits right. I mean, I am not sure if Princess is "best in class" on any one thing (well, I take that back, they do have, by far, the best Pizza), but they are a pretty consistent 8/10 in most everything that they do. Also, the ships, with one big exception, are all pretty consistent, so you know what you are getting. Food is decent to very good and service, in general, is pretty good. I never feel like I "have" to eat in specialty dining. Now all that said, I will say that there is a big difference in the newer ships (Royal class) versus the older ships (Grand Class) especially in terms of the buffet area. The buffets on the newer ships, in our experience, have been much better in terms of quality and selection (not that the Grand class is bad, it's just not as good as the new ships). Also, the Royal class ships have an Alfredo's, which is an additional included pizza/Italian restaurant off of the piazza, which is consistently excellent. We also like their International Cafe, which is pretty much like what Cafe Promenade would be on RCCL if it were expanded to 3 cases instead of 1 and the food was much better
The International Cafe is 24/7 and always has something good to eat as well as excellent salted caramel lattes. I also like on Princess that there are self-serve laundromats, no "checking-out" towels, and that room service is still included. In fact, with their medallion (which, admittedly works better on some ships than others), you can order food and drinks to anywhere you are on the ship (We sat on the back of the ship leaving Juneau and had stuff brought to us for 2 hours. It was amazing.) Also, we are elite with Princess, so we get free laundry. That's a great perk on a long cruise!
Last thing is price. We'll be back on our favorite ship,
Regal Princess, early this year for a 12-night British Isles cruise. Now, we are doing 4 in an inside (they had a 3/4 sail free) and all of us have the Princess Plus package, which includes gratuities, wifi, and the drink package for all 4 of us and the total for the 12-night cruise with all of that including port fees and taxes was right around $6,000. Hard to beat that...
So... Go try a bunch of lines. You may find that they all do something well and you may enjoy getting to have a bit of variety! I've never done Celebrity and am looking forward to trying that sometime as well!