Which one would be more xp/hr?

And where can I use chins at aside from the MM cave? There was another spot in wildy with armored skeles or something that were ideal, but I forgot where they're at. Are they good still?

Chins are always better if you can group the NPC's in a multi area.

The skeles are under the chaos alter

Gray chins , I use to get 70K+ xp per hour at MM Cave with only 58 or 60 range.

There are no skele's under the Chaos Altar. Your best bet would be the Shilo Village skeletons. But it's alot of effort because you need to lure them every 2-3 minutes.

I would just use a msb and rune arrows/or armcbow and broad bolts and afk at Nmz for around ~55k xp/h at 80 Range.