My wife works for M&S and I have been sampling a lot of their crisps for some years now. I have to say a lot of salt and vinegar (the crisp lovers go-to choice I think you’ll find) crisps have lost their edge over the years but the M&S varieties such as their twirly ones can pack a real punch and have a proper crunch too.
I think I have the right to comment on such things – I’ve done my time eating crisps on an industrial scale over the year, including going to a nearby 24hr garage in slippers and dressing gown to spend my last few pennies on 11 packs of Pickled Onion Monster Munch at 3am in the morning and eating every single pack one after the other without stopping. Perfectly sober too!