There are other options like Garmin and Amazfit, but honestly the UI on both of those are pretty awful, especially compared to the slick Pebble UI.
I absolutely hated brushing the iWatch screen and triggering random crap and there was no other way to interact with it! Garmin's w/ 5 buttons and transflective (sunlight-readable) displays have been the closest alternative, and they have a pretty cool "touch-screen alt mode" which you can access via press+hold on two of the diagonal buttons to enable/disable (or automatically starts if you open up the "maps" app for dragging it around).
Long battery, sunlight readable, buttons.