Personally, I am a big fan of wax. Regardless of the shine I get after polishing, I find the sheen provided by waxing amps up the realism. I use Tamiya wax. Wax must always be the last thing you do to a body. Decals, paint, glue, etc won't stick once the thing is waxed. I have never had an issue with wax having a negative effect on decals. In fact, I find it improves their appearance.
It's probably worth mentioning here that I rarely ever clear coat my paint, again for reasons of realism. To my eye, clear coated paint generally looks unrealistic, and perhaps that is the reason the waxed finish looks good to my eye. Metallic paints being the exception, of course, but I mostly paint in solid colours.
I also polish and wax the kit glass which does great things for improving clarity and reducing optical distortion, and it makes removing fingerprints easy.
Just another POV.