The Valar

[Voralphion]

Tickle-me-Ulmo played a reasonable role, although one wonders why he bothered, his games were as tricksome as a Greek deity, the most fickle of the bunch.

With this I disagree. If it weren't for Ulmo, Tuor would never have gone to Gondolin, meaning he never would have met Idril and Earendil wouldn't have been born. If it weren't for Earendil, the Valar would never have come to ME to defeat Morgoth and all of ME would slowly have come under his control.
I think Ulmo did the most of all the Valar to help ME, certainly more than Manwe.