My protank 2 mini also had a metallic taste for a while when I first got it, but that went away after a few refills/cleans. Must be something left over from the manufacturing process maybe?
I've started using the plastic ones again, specifically the Kanger T3S. At about $5 each, I find the vapour production and flavour to be really good, and they seem to be "warmer" than the protank mini, even though they're a bottom coil and similar size. I've had no issues with leaking, clouding, cracking or anything else, and they work really well with the Innokin iTaste 3 VV/VW batteries I'm using. The only drawback is that the tips aren't removable so they can get a bit of gunk buildup that's hard to clean.