Me I love my stock trailer!
I'm in N. Fl. So it's never too cold here, instead I need a trailer with good air circulation, so I have a 16' white Bee (K&K) stock that's 7' high with a cut gate so I can completeluy divide the trailer in half or tie up 4 side by side. Mine has a solid roof. I don't like the canvas roofed ones.
If you're in a colder climate they have the ones with inserts to put in the slats to keep the drafts out. What's great about a stock is you can load it up with hay, shavings, furniture even. They are soooo versatile.
They are also more affordable than a slant for the room you get.