Rash- Level 70
HP/MP: 14,500/150
Common Location: "Leafre: Minar Forest: West Border", "Leafre: Peach Monkey Forest", "Leafre: West Leafre Forest"
These guys are your best bet. Easy to kill on a fairly consistent rate, and you'd be undoubtedly fine here. Recommended map for them is "Leafre: West Leafre Forest". I think these guys inflict some status, but I don't think it was much to worry about.
Beetles might be annoying if you can't kill them fast enough. They have super physical defense, so they might be annoying.
Next is the level 76 Dual Beetles. I'm sure you can handle them easily, and they just use super magical defense. It's not hard to handle these guys at all at your level.
Dual Beetles- Level 76
HP/MP: 18,000/200
Common Location:" Leafre: Leafre : East Forest", "Leafre: Minar Forest: East Border", "Leafre: Beetle Forest"
Out of these maps, I'd say "East Forest" is the best. I'll note that all of these maps have mixed spawn, but oh well.
As for drop rate- the rate is the same. Really, all it boils down to is how fast you can kill these guys.