General

Just go Dimensional Portal and then when you run out of turns just go Sleepywood
my suggestion

50-55 Copper Drakes in Sleepywood (the first map has 4 flat platforms with nice spawn)/ White Fangs in ElNath (the map before the yeti place has 3 platforms full of great spawn)
55-60 Hodori (Korean Folk Town the first tiger area has nice spawn and the monsters there can be killed in 1-2 hits)
60-63 Robo/ Master Robo (ludi)
63-70 Barnard/Zeta Greys in Omega Sector - Kulan Field 2 has an extra portal and the hidden map has nice spawns. the greys are also quite weak. If you have a good AoE attack then Zeta Greys in Kulan Field 3 have amazing spawn (the top left corner of the map has the most). For non-mobbers Zeta Greys might be hard to hit because they fly.

If you get bored/ don't like grinding, head over to Ludi PQ for great exp and nice glasses (+1 All Stat). If you need a medal, go to Chryse. The boss might have some good drops, but I'm not really sure. However, there's an insanely long questline to finish before you can actually kill him in a party (PQ).

Oh by the way I play MapleSEA. So this might be outdated for GMS.

Hope I helped

Tested out yesterday on my phantom :

King Pepe at the end of Mushroom kingdom all the way to 70. He nets about 5K exp on 1x exp. Meaning if you can kill him under about 4-5 seconds, it's slightly lower than Toy room with jesters. Ofc, It doesn't beat chimney jesters, but at least you don't have to fight for a map.

Took me about 1-1,5 hours from 30-70 on 2x up to 55, and then i got a 1,5 coupon, so 3x from 55-70.

[quote=Typhlosion]Last time I check Ariant is a level 70+ area now.[/quote]

it is but if u have high attack and can hit multiple enemies multiple times u should be able to kill them in 2-3 attacks with 1-2 misses in those multiple hits.
i found the exp worth it.

ariant, 50+, flat maps, good spawn

PQs
Ludibrium robos, trojans
Omega sector aliens
Yeti pq until 60
Chryse
Sleepywood