[MRM]

It looks like you have an old wood window with true divided lites. I don't think you're going to get a big upgrade in efficiency by replacing just the glass. I think you'd have to replace the frame and use simulated divided lites to really get energy savings. I can't think of anyone who offers an off the shelf true divided light bay window anymore. It's too expensive to manufacture true divided lites.

My vote is to simply replace the broken pane and the two that are cracked with replacement glass that matches the original and let it be. If it's too cold or the draft bothers you, cover the inside with one of those clear plastic films you can buy at Home Depot.