I use the King Alfreds. The building is on its last legs and a bit tatty but the gym equipment is excellent and the showers work and are hot. Also, and this is a huge plus...it is rarely busy. In 4 years of using the place I've never had to wait for a running machine.
I've been a member on and off for ten years, it's great if you're serious about weight training. It can be intimidating with the amount of big blokes who use it, but there's skinny kids and really old guys who frequent it too, there's all levels of fitness and physiques there.
I like it as it's as far from the LA Fitness-type gyms as you can get (I'm not knocking those, but they're not for me and cost an arm and a leg), loads of free weights and everyone leaves you alone if you like to train alone and with intensity - not many fit birds to distract you too! All the Cheetah regulars I know there are friendly and I just get on with it.
Ronnie Davies runs a boxing gym there too, so there's a diversity of people who use it, and Mums etc come in to use the cardio room without ever descending into the testosterone pit where the monsters train
If "pikey" means "working class" then it is exactly that