Travelpro Flightcrew3 22" it fits just fine in all the 737 bins, except the forward bins in over row 1 in F which are smaller due to curvature of the plane.

Be aware though it barely fits the sizers of other carriers. AS allows 10x17x24 while AA,DL,US & UA only allow 9x14x22 which is pushing it and it barely fits their sizers. Remember that in case you will be flying other carriers.

Here is the 20in newest version if you want to guaramtee it will fit in overhead on mainline flights with all carriers. $129 through crew shops. You don't have to be crew to buy, or they just dont care.