Welcome to this corner of the moulded fibreglass online community, Frank.
Your background story is quite similar for many of us here, so lots of folks can relate to it.
Both the 21 and the 5.0 are excellent trailers, and share many of the same features. The two biggest differences, are the layout of the bed and bath, and of course how they get towed.
Take lots of time and go through some of the past posts, and you will get lots of great information there, as well as lots, and lots of great input from the membership as well.
Have fun making your decision, and don't forget the wait time to take possession is well over a year from the time ordering right now.
2017 Escape 5.0 TA (someday soon, I hope
2015 Ford F150 Lariat 3.5L EcoBoost
2009 Escape 19 (previous)
“Most folks are about as happy as they make up their minds to be.” — Abraham Lincoln