I have recently bought an Emma Original mattress, basing my choice on Which? reports. I knew I was taking a chance as I hadn't tried it, but they say that you can try it for up to 100 days and if you don't like it they'll collect it and refund you.
Well, they're not getting mine back, I love it! It's made of various types of foam in different layers, and it's the most comfortable mattress I've ever had. Quite firm and yet totally supportive, very flat
and smooth with no bouncing or unevenness. I sleep really well on it.
They are not cheap but every so often they do an offer with, say, 30% off.