My wife had my old 5X and I replaced it with a Pixel XL which I've had for 12 months now but, having handled the 5X again today, I do wish I could have a Google phone that size with better battery life. Ordered a Pixel 2 but changed my mind and replaced it with a Pixel 2 XL order as I've lived with the XL for a year. Bigger battery wins.
I must be the only person who gets great battery life with the regular Pixel. I regularly get 4hrs SOT with 14-18hrs up time and around 10-15% remaining. That's actually the best I've gotten of any phone I've owned, and I had the Droid Maxx and Droid Turbo, which had 3400 & 3900mAh batteries respectively. I could maybe hit 3hrs SOT with them.
The thing to look at is that while the regular Pixel (or Pixel 2 for that matter) have smaller batteries than the XL models, they also have a smaller screen at a lower resolution, and that helps battery life a lot. The screen is probably the biggest draw on battery (except for camera maybe, but the screen is used more than the camera).
The XL is a good looking device, but I just can't go back to a phone that size again. I had the 6p, and while I could deal with it, the regular Pixel is much easier to handle. Since the screen is only 5", it doesn't need a high resolution, and I don't do VR so that's not a concern either.
As for the OP, I wouldn't mind a polycarbonate phone, if they went with something along the lines of the old Nokia Lumia models. Those seemed to be pretty solid, they looked good, and I'd imagine different colors would be easier to do on polycarbonate than anodizing aluminum.