I swear by Spectacle. After trying a number of other wms, this is the one I ended up using for more than a year now. It strikes a good balance for me between features and simplicity, and the keyboard shortcuts are intuitive and don't clash with other apps (like iTerm, Fantastical, etc).
You should try BetterTouchTool. It can do everything spectacle can, but has a lot more features, and support for trackpad gestures, and other nice things. It even has draggable window snapping like Windows/Ubuntu Unity.
