I've tried several different types, and the thing with this whole get up is, you just really have to find what works for you guys the best. This is one area that is totally trial and error. Especially the harnesses.
Some things to remember:
Remember to use lots of good lube.
He's not going to like it at first
In my experience, if you can get a guy past the first few minutes, and maybe have him masturbate while you are doing it, it makes a HUGE difference. My husband insisted that he HATED it the first time. But I got him drunk and did it again, and he complained afterwards, but not as much. He doesn't ask for it now, but he doesn't argue when I ask to do it either. If you haven't gotten one yet, you can use code TUE at checkout for 15% off