a lot has to do with how you're going to use the trailer and what you'll be towing with.
if you want to "camp", instead of "RVing", a shorter trailer is a good idea since camping usually means in state/national parks that have smaller sites and you're taking shorter trips.
if you plan on RVing or full-timing, a larger trailer will be more suitable, since you'll primarily stay in RV parks/resorts and be living in them more. these places will have pull-thru sites and be longer for bigger rigs.
and having an adequate tow vehicle is a huge factor. if you've had experience with a 5th wheel, a bigger TT shouldn't be that hard for you to handle. but you won't have the high ceiling that the 5th wheels have, with a TT.
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC