Skips and Quavers are mouthfuls of magic, likewise all Salt and Vinegar crisps (especially the following brands: Walkers, Seabrook, Kettle Chips and McCoy's). Pickled Onion Monster Munch were great, and I also enjoy the occasional crispy rendezvous with the Ketchup and Cheese and Chive flavours made by Seabrook.
Although not a crisp, an honourable mention goes to Smiths' Scampi Fries