I need to get some new undercrackers. M&S was always my go to, but are there other places you would recommend?

I need a knicker overhaul as my backside is spreading at an alarming rate. I was always fond of M&S pants but I'm wondering if going back there is just underwear apathy. Are there any other shops or brands I should try? I'm not a fan of the thong (unless it's a flip flop) or anything too style over substance. I'm after workaday drawers. Thank you.