For me, it depends on if we're talking about sexiness in the movies or in real life. Like, Hugh Jackman is super sexy, but I don't find him attractive as Wolverine at all. James Marsden is hands down the hottest actor, but he wasn't super sexy in the movies (except for X3).
So in the movies:
1. Michael Fassbender's Magneto
2. James McAvoy's Xavier
3. Daniel Cudmore's Colossus (as small as his scene in X2 was it still earned him a spot in the top 5)
4. James Marsden's Cyclops
5. Shawn Ashmore's Iceman tied with Nicholas Hoult's Beast (pre blue and furry)
In real life:
1. James Marsden
2. Hugh Jackman
3. Michael Fassbender
4. Daniel Cudmore
5. Shawn Ashmore
I didn't include any of the new DoFP cast yet, but Adan Canto is probably hotter than all of them. Here's hoping they give him a meaty (
) role in the movie!