opinions on rubber unions

I am going to connect 1.5 inch sched 40 pvc P trap to 1.5 inch copper drain line for my tub.

whats everyone's opinion on the rubber unions with stainless clamps?

this union would be laying horizontally?

i would like to never have to revisit this once it's done.

any better options out there to join the sched 40 pvc to copper?

It seems a little odd in the application you're describing. However I'm not a real expert and I can't see exactly what you're doing, so who knows. I know that in situations where I could have used them I just put a threaded PVC fitting that the copper screwed right into. But since you asked for opinions on the unions (and nobody else has answered yet).
I know that my brother has some in his basement and has for years with no problems. Also I've spoken to a plumber about them in the past and he said at the time that they were commonly used and there's really no problem with them. So that's what I've heard. Good luck.

coupling

The rubber ones with a hose clamp at either end are not intended to be used above ground. The "No-Hub" transition type with an enclosing band, specifically made for the two different materials is the one you need.