I prefer Arcoxia (Etoricoxib), it is a selective COX-2 inhibitor and therefore has far less chance to cause any stomach issues, if at all.
I have also found it be far more effective than Ibuprofen as an anti-inflammatory and pain killer and is very light on the stomach and only needs to be taken once a day, instead of 3 times a day.
It also does not cause dry eyes, which Ibuprofen and other NSAID's may do (except Aspirin).
Another excellent NSAID is Xefo (Lornoxicam), another COX-2 inhibitor and is very similar to Arcoxia. Celebrex is also good.
Personally, I have found Arcoxia (Etoricoxib) to overall be the most effective.
Also, Aspirin is underrated in my opinion and possibly one of the more useful NSAID's for tendon injuries.
In terms of muscle gains, I don't think they make a difference and I have not noticed any differences when using them.