Does Gender matter? I mean most of your options were girls, don't really care if it's just personal preference or the class choice or whatever just wanted to ask

For me I wanted to practice the complexity of tge features of women but if the character is striking enough I won't mind any idea.

I'd vote Samus then

I would have to go with sheik.

It depends on what you want. I know very little about modeling, so this advice is based on guess work, for all I know this won't really help you. Sheik has many little details that could make it hard to focus on the anatomy, but it could be good for practicing little details while not drawing the eye too far away from the form. Whether you make the details on the clothing 2D or 3D is up to you. Samus in her zero suit has comparatively few frills. She is probably the best if you want to focus purely on the body. Ellen would be good practice putting real life proportions into digital format. Spiderman is similar to Samus, but with male anatomy. He could be useful if you want to work on masculine characters without having to worry about getting the face right, as I believe that might be one of the hardest parts.

On other potential models, I have some ideas. It's okay if some of them are shirtless, right? Cammy (Street Fighter) Snake or Raiden (Metal Gear) Johnny Cage (Mortal Kombat) Tracer, Widowmaker or Genji (Overwatch). I could probably think of a lot more, but too many choices can also cause problems.

I hope you find this advice useful. You know what you want better than I do.

thanks for the comments. I do enjoy Venom Snake and Johnny Cage.
I personally would love to do a zero suit samus with the more realistic face that Metroid prime one had (which I thought her face was a perfect match for her character). Was even thinking of mixing the elements of Ellen with Samus to give off further uniqueness.

I second the vote for Samus, if you're going for something that will show off anatomy. Doesn't get much better for that than a suit so skin tight it goes by the designation zero.

Captain Falcon's body is chiseled out of diamond
Uh, maybe Black Mamba from Kill Bill?

Daredevil