Expert mining gloves: iron or coal?

So I’m 76 mining and I want the expert mining gloves (sooner or later), so I thought better to get it before the big sand grind.

My cash stack isn’t very healthy (not big enough to sustain misc yet atm), so take that in mind.

Do I mine iron for like 16h (ending up with 18k ores - used for cballs - but then I’d need to get coal somebow) or do I mine coal for like 25h (ending up with 11k coal - used with the ores that MLM shits out for cash)? Or are any of the other ores a decent option as well?