1. Scarlet Witch is probably the most powerful. She even sent Vision through like 4 layers of the Earth.
2. Vision might be #2, with his vaguely-defined godlike powers.
3. Spider-Man. Might be just as strong as Captain America, considering him stopping a flying car in midair, and also holding up the tower Cap knocked over on him (albeit struggling with it). Also incredibly acrobatic, and his web-shooters allow him to go airborne in a way no one else can do without mechanical wings or an Iron Man suit (except Vision and Wanda levitating themselves).
4. Captain America. The Winter Soldier, Black Panther, Spider-Man, Iron Man, etc. can all take him on in a fight, but I still think Cap comes out ahead for sheer strength (pulling down the helicopter). He is still a strategic fighter, which is how he still managed to get the drop on Spider-Man and Iron Man at moments despite them both arguably being more powerful and/or having more gadgets at their disposal.
5. Iron Man. Out of his suit, Tony is a normal guy who's not any super hand-to-hand fighter or anything. But his suit comes equipped with tons of gadgets, he's a tech genius with more goodies than Q, and he's beaten The Hulk and gone toe-to-toe with Thor before, and was beating the **** out of Captain America until Bucky's intervention. It took Cap and TWS tag-teaming him to take him down, barely, and they both got badly hurt in the process. I still put him below Cap though, because his power is almost entirely reliant on his technology. He's nothing special outside the suit and without his gadgets.
6. Ant-Man. Like Iron Man, he's not an especially skilled fighter in and of himself, but his suit gives him a major advantage, especially when he turns into Giant-Man. Plus he gets people with blitz attacks where they don't know where the **** he came from, and even got the drop on people like Spider-Man and Black Widow who are both much better technical hand-to-hand fighters than he is.
7. War Machine. Can basically do everything Iron Man can do, except he's not the tech genius who comes up with it, just the right hand man who backs up Iron Man.
8. Black Panther. Some might be surprised I'm putting him so low. As a hand-to-hand fighter, he is extremely formidable and the most acrobatic fighter apart from Spider-Man and arguably Captain America, and even kicks The Winter Soldier's ass. Also has a bullet-proof Vibranium bodysuit and steel claws. But he hasn't demonstrated the strength of Captain America, nor does he have the firepower of Iron Man or War Machine.
9. The Winter Soldier. Again, could arguably be rated higher, and can give Captain America a hard fight in hand-to-hand combat, but like Black Panther, I don't think he has the sheer strength of Cap (a lot of it comes from his metal arm), nor does he have an armored suit or gadgets. Also Black Panther pretty much wipes the floor with him on two separate occasions.
10. Falcon. His wings are his major advantage, though the addition of Redwing also lets him get the drop on Spider-Man and one of Rumlow's goons. Without the tech, he's a decent hand-to-hand fighter but can't hold up against the enhanced people on hand. The Winter Soldier throws him around like a rag doll.
11. Black Widow. Skilled hand-to-hand fighter, can take down some of the others in one-on-one hand-to-hand combat, and has a bag of tricks including borderline magic phone apps, stunners, and face masks, which she has employed resourcefully, but has no superpowers. Formidable to average people, of course, but on the low power spectrum, relatively speaking. The couple times she's tried to take on The Winter Soldier, for example, she got thrown around like a rag doll and only survived by either dipping into her bag of tricks (momentarily disabling his metal arm) or by someone else coming to her rescue (Cap in TWS, Black Panther in Civil War).
12. Hawkeye. Meh. Can't miss with his arrows and can go toe-to-toe with Black Widow hand-to-hand, but even she was winning until Wanda intervened.