Most high quality tanks are using glass or pyrex, the others lean towards polycarbonate. It's more heat resistant and chemical resistant than regular plastics. It's also scratch resistant so there's less worry about scratching during refill melting scratched particles.
Using polycarb tanks for a bit now, I can attest to them not getting too hot (can easily touch them without burning). They have a "glass transition" temperature of about 147C, which is a fair bit higher than the coil gets (have read anywhere from 45-80C but haven't found solid numbers yet.
Something I would be more concerned with is the o-rings that are usually used to seal the tanks, as they are in direct contact with the carto. Also cartomizers use cotton/poly filler. Clearos and other wick tanks use a variety of materials for wicks. Just something to keep in mind, as Dishevel said: there's more than just the tank itself involved.
Though I've not had personal experience with them, check out phiniac tanks for a wide selection of pyrex options. They have a higher price tag than polycarb tanks, but you pay for material and quality.