When it was time to replace it I did some research and landed on latex, because it holds up for a long time, is organic and hypoallergenic, and sleeps cool (I’m a hot sleeper).
Ended up buying from sleeponlatex.com based on reviews and their excellent return policy - best there is for latex as far as I could tell.
Very, very happy with it. It did take at least 2-3 weeks to adjust too, because it’s firm (even if you get a medium) - you sleep on top of it, not in it, meaning it doesn’t wrap around your body. 10/10 would recommend.