Celebrity and - Fred Olsen (don't knock it till you try it)
We have sailed both - Celebrity - larger ships, elegant - not many kids (no slides etc) nice restaurants modern rooms. Expensive.
Fred Olsen - smaller ships, homely, not any kids usually, lots of daytime activities (quizzes, craft classes, talks etc) dancing for single travellers, posh coffee shop, library. Reasonable cost. Great food.
Contact me if you need more info x