Best jig for casting for bank fishing from

shore in open water?

Round (finesse) style head or and arky head.

Siebert Outdoors, Grid Iron G2

 

https://siebertoutdoors.com/products?olsPage=products%2Fgrid-iron-dock-rocker-jig&page=2

Open water, I'd go with a round finesse jig. War Eagle jigs are my go to. 

Fishing jigs from shore means casting out into deeper water and retrieving back uphill where they can snag easily.

My suggestion is select a jig with a high quality hook and the lightest weight you can cast easily. GYCB (Yamamoto) makes Hula Grub and jig that is designed to be worked at various angles without snagging often. The Twin Tail Hula grub 4" or 5" on a 1/4 oz or 3/8 oz Hula jig has Owner hook, weed gaurd and makes a good spider jig combination that is about $2 each including the Hula Grub. 

Tom

Siebert Jigs