After multiple scope failures using brand name (Excalibur & TenPoint) crossbow scopes. I switched to a Leupold 2-7x shotgun scope this year.
It has a little parallax at my sight-in distance (25 yards), but I can hold 1" groups with it from a bench rest.
About 100 shots so far and it's still holding up fine.
If it continues to hold up I plan to send it to Leupold next spring and get the parallax adjusted to crossbow ranges.
With the variable power I've been able to adjust the power (2.5x with my Excal Phoenix) so the top & bottom duplex "posts" are good for 15 & 35 yard sighting.
So far this season 2 shots at deer with it and 2 clean one shot kills with good arrow placement (just where I wanted the arrow to go).
One at 17 yards using the top duplex to sight, and one at about 20 yards using the crosshair to sight.
BTW - I use a 25 yard sight in, so a "center of the kill zone" hold will keep the arrows in the vitals (+/- 3") from 0 - 30 yards with my bow.