Though I have to say regardless of the region (except Japan of course) all the NES Megaman boxart looks awful...none of it really reflects in the in-game graphics and I don't think anyone really had any concept of what Megaman looked like except for Inafune.
I think noone would disagree with you there, least of all me. However, out of an exceedingly bad bunch, the Mega Man 3 cover is pretty much the best Mega Man cover the Europeans ever had. Mega Man 4 and 5 (6 was never released in Europe) had the same boxart as the US originals, except for one thing: Mega Man's face. On the US versions, he has a big, fat grin. The European versions have a much more anime-like mugshot of Mega Man.
BTW, here's another preview, this time of EU Mega Man 2...

Need I say more?