We had Tyrrell's crisps on a course at IBM in Edinburgh last year - I didn't think much of them. I'd personally choose Seabrooks, but everyone's tastes are different so it's probably a case of giving then a go and seeing what you think.
Seabrook have taken the brave decision to make their crisps WITHOUT one of the worst, most nauseating ingredients on the planet; E621 or Monosodium Glutamate. I am totally allergic to this substance and it gives me hideous migraines so can't go near it but I'm pleased to give my custom to companies like Seabrooks who've made the decision to go ahead without having to use that cheap, tatty, pathetically easy method of faux-flavouring crisps. YEA SEABROOK!