This question gets asked a lot in this forum. The answers tend to be the same with everyone chiming in with what their "favorite" cruise line is. But to be honest with you, it comes down to personal taste. You have already cruised Carnival on the Conquest and you seemed to have enjoyed it. (we lean toward Carnival because of the value we seem to get). I am looking at Royal Caribbean for our next cruise because of the advise I have gotten on this forum AND for the "something different" factor. Therefore our upcoming cruise is an NCL cruise and I am trying to figure out if I want to book an RCCL next summer, but I'm finding doing that will cost an addtional $1000. (To get on the Voyager class ships). But it boils down to what you are comfortable with. RCCL and CCL are probably the most popular with Families. Princess/Holland America and Celebrity are other choices. If you are interested in doing something different, try a different line.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise, Magic 1/14
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013