what are the perfect levels for LFG dungeons?

[Narmenel]

I know the sweetspot for low dungeons is level 25, I figured that one out by trial an error but what about 30-40, 50-60, 60-79?

[angrylol]

Just go for max level in bracket you want your twink to be in. But it's unclear what are you even asking here.

[OhieMitzen]

Guessing they want to farm dungeons for specific loot via RDF system to get twink items.

[angrylol]

mm, dungeon finder shows the level range for each dungeon(click "specific dungeons" to see it), so if you need an item from dungeon 49-57 or whatever, just disable exp at 57 and farm it until you get what you need.