If you're poor or don't care; Mayfair.
If you're a hipster; roll your own with GV.
If you're nearly a hipster; Malboro.
If you're a bit chavvy; Lambert & Butler.
If you're over the age of 40; Benson & Hedges.
If you're over the age of 60; Silk Cut.
The actual most popular UK cigarette was Lambert and Butler when i last checked a few years ago. Since the massive shift to lights and the fact every bastard smokes them, i think it's now Marlboro Lights. Marlboro as a brand has more market share worldwide than the subsequent top 4 combined.
There are no 'best value for money' cigarettes in the UK, we're completely screwed by taxes here. 50g costs £12 here, in Belgium i got 400g for 15 Euros. At Gatwick duty free i got 400 Marlboro reds worked out at £2.50 a pack, in store it's £7 in some places and over £6 elsewhere.
But the best taste? Aha! I tried practically all of them since i started smoking. The subsequent list are 'regulars', lights don't count as far as i'm concerned, so don't confuse Camel with Camel Blue (lights)!
Marlboro, Pall Mall, lucky Strike (they're toasted!), Camel, L&M, Dunhill and American Spirit are my top brands. (I did try Londis own brand... never again)
I usually smoke rolling tobacco though, and the UK market is pretty crap for that. If i do buy here it's usually american spirit or cutters choice, if i'm abroad then L&M, Pall Mall or Camel will suffice. I tried Top as well, that was pretty good
I dont smoke anymore, i physically cannot stand the taste of tobacco or the nicotine rush anymore, makes me sick everytime. Back when i could still stomach it, Lucky Strike was my favourite. Drum or yellow Golden Virginia were my favourite rolling tobaccos.