As regulars on here will know, I choose to only sail on the smaller ships (although tried Azura twice).
I like the more intimate feel with, generally, smaller public rooms. I have done a lot of solo cruises in the last 11 years and love that when walking around a small ship you continually bump into people you have previously met and chatted with. I like the fact that you don't spend half the day walking around the ship just in order to get between venues. I love walking whilst exploring ashore but walking what seems like miles just to get from, say, the restaurant to the theatre, is just dull. On P&O's smallest ships I love that there is a full, wraparound promenade on one level, close to the sea. I enjoy that there are fewer eating venue choices as when on a cruise I don't want to have to think "where should I eat tonight". My needs are simple and the smaller ships meet them.
Hopefully that's plenty of positives for you ICF...