The difference is RCI is mass market and Celebrity is premium. Celebrity has a totally different touch/feel about it. I love Celebrity. They are very refined, the service is superb, the ships are elegant. I would try one of the Millennium class ships. That would be the Millennium, Summit, Constellation, or Infinity. The Thalassotheraphy pool area is heaven.
Another thing to consider: You're not far from being a diamond member. If you book a cruise on Celebrity, you won't get a cruise credit for Royal Caribbean. They offer a lot of perks to diamond members.
Cruise credits do NOT combine. If you book a cruise on Celebrity you won't get a cruise credit for RCCL. If you are a gold, platinum, or diamond member on RCCL, you will get the same status when you sail on Celebrity; and vice-versa. Cruise credits stay with the cruise line you book. You can call the Crown and Anchor Society at 1-800*526-9723 for more information.
You are correct Sonny as I have checked on our Celebrity cruises and RCL and Celebrity do not honor each others cruises toward the total number. We have sailed Celebrity and although they are what is being said, we do prefer to go RCL.
I have good friends that just turned diamond plus. They tried Celebrity last year and feel the same as you about prefering RCCL. I didn't think I was wrong on the cruise credit sharing. If they ever change their policy I'll try cruising on Celebrity. I'll be on my 40th cruise next month. I'm just starting to get upgrades and I'm lovin it!