A couple of things that I did not see specifically mentioned. First, a travel trailer will put 10-15% of its weight on the tow vehicle while a 5th wheel will put 20-25% on the tow vehicle. This can be somewhat confusing as the tow rating for a given tow vehicle is often greater for a 5th wheel than for a travel trailer. However, a tow vehicle may be under its payload capacity with a travel trailer and over its payload capacity with a 5th wheel of the same weight.
In my experience, many travel trailers are built for the weekend/vacation market. It seems there are more higher quality 5th wheel choices with things like higher R value insulation, dual pane windows, etc. (at a higher price of course).
Size may matter. While travel trailers over 32' box length (the living quarters without the tongue) are becoming more common, I think there are many more models in shorter lengths. Fifth wheels less than 30' seem to be relatively rare.