I've only had the Watch for a week, so I haven't settled into a final configuration. Here's what's working for me so far.
I've removed glances for anything that's a complication on my Modular face: Weather (current temperature), World Clock (EST time), and Calendar. After all, they're one tap away, so why use a swipe as well?
I haven't ended the day at under 50% battery, so I've removed that glance. In the unlikely event that I ever needed to view it, I can always start to set it as a complication.
All my investments are in an index fund, and I'm not a day trader, so I don't need real time stock updates.
I have four glances at the moment: Now Playing, Transit, Citymapper, and Maps. Once I figure out whether I use Transit or Citymapper more, all remove the other one. Once Maps gets transit data in LA, I'll probably remove both Transit and Citymapper.