I love my Jade mat! I don't slip even when extremely sweaty!
I second the Jade mat.
Jade Harmony & Manduka eKO is perfect for hot yoga....
This is a brand new mat that just came on the market: https://www.atinybitfit.com/
It's specifically designed for hot yoga, so I'd recommend checking it out. I haven't tried it yet but have friends that are obsessed with it.