Stock Screeners / Scanners

I'm a little confused about the state of stock scanners/screeners which I'd like to use to pick stocks (otherwise I'd just feel like I was putting a finger up to the wind).

Not many I've seen allow me to customise based on random indicators (such as donchian, for example), or use specific settings I'd like to try to make sure I get to choose the ones I'd like.

Does anyone know of any resources/services which allow for this (paid or free)?

Thanks