Sort of depends on the type of spots you'd be hunting, but for general US coin shooting at sites with average soil/iron/trash conditions, I'd rank them in this order:
1) Etrac
2) Nox 800
3) XP Deus
The reason I'd put the Etrac first is because you said you're mainly a coin shooter. In my mind, this means exactly what it sounds like.. Cherry picking coin signals while skipping over most other target ranges. FBS tones, accurate TID & accurate depth meter gives you a LOT of information about the target. Makes it easy to pick out deeper coin signals, skipping right over the modern/unwanted stuff and quickly moving on to the next desirable coin target. Huge advantage. When it comes to this type of hunting, nothing beats an FBS detector IMHO.
For someone who is more of a relic hunter I'd rank them in the exact opposite order. Deus, Nox, then Etrac last. The Equinox remains in the middle because it's pretty dang good at both coins and relics, even though it wouldn't be my #1 pick for either category. IMHO, where the Equinox really excels is picking out good targets from extremely trashy "hunted out" sites. It doesn't have the most accurate or stable TID & depth meter, but it makes up for it with its ability to tag some tough targets that other machines simply cannot see due to co-located junk.
A few other things to consider:
1) Etrac requires a slower swing speed in trashier sites.
2) Etrac is noticeably heavier.
3) Equinox and Deus will hit small low conductors harder.
4) Nox is good to go for water hunting.
5) Learning curve (IMHO) from easiest to most difficult would be Etrac, Equinox, Deus. Deus is a great machine but it took me a little longer to sort out iron vs good targets. YMMV.
I've put lots of hours on all three of those detectors but keep in mind everything here is just my opinion. Others may disagree.