I tend to lean towards a TT. I like the flat floor, generally less entry steps. Lighter hitch that doesn't require holes being drilled in the bed (factory 5th wheel prep or not).
I like being able to use the bed of my truck while towing (not just 3/4 of it)
TT's tend to be lighter...I.e. The biggest TT 's generally gross around 12k...fivers can start at 12k lbs but there are becoming more and more lightweight fifth wheel options. I like the weight distribution hitchs. A properly adjusted weight distribution hitch with a properly loaded travel trailer and a properly loaded truck will have a great experience. The hitches generally come apart in three pieces, two spring bars and one hitch head.
I did leave off that if you want a really high end product then a fiver is the way to go because it's hard if not impossible to find a really high end TT other than an Airstream. There are some really nice TT's made today but not a whole lot at the Mobile Suites or Jayco Pennicle type levels.
They sell a lot of TT because the barrier to entry is much much lower financially.
Oh, I also forgot...there are more vehicles that can tow a TT...so if you get in a tight spot and need to pull the TT with a Full Size SUV or Van you can. With a fiver you have to have a truck with a fifth wheel hitch. Just something to think about.
Either will serve you well...it's whatever strikes your fancy.
Thanks!
Jeremiah