who would win master chief vs Samus Aran?
-Recharging Combat armor
-surgically altered body/muscle structure
-cortana AI assistance
-keep in mind chief is not like the newer class of spartans who are merely soldiers with cutting edge combat armor. He's a child soldier whom earth governments have invested billions in training.
Samus Aran
-Armor developed by (now extinct) alien race the chozo.
-Depending on upgrades this suit of armor can become radically more powerful(gravity, light, dark suit varations)
-Attachments include ice missiles, grappling hook, particle charge cannon as well as the ability to jump for hundreds of yards at a time(with the spin attachment)
-Samus has also been a child soldier, adopted by the chozo. This gives her unprecedented tactical advantages that human soldiers aren't typically trained for.
-She is a bounty hunter first, so motive may be questionable. She may choose to not kill cheif if she can earn more for him alive
-She can morph into a ball
In my opinion you have to go with samus. Master Cheif has more brute force, especially if he can get within melee striking distance of samus, however, with ice missiles (that would freesze chief instantly) it seems implausible that he would come out the victor.