Gyms and fitness (London)

Hi Everyone,

I'm wondering if anybody has advice on which gyms are good to join in London? I'm an Anytime Fitness member in Australia (global access) but it seems they do not have a big presence in the UK. I've also found groups like Nuffield which seem great, but fairly expensive.

I have a flat in the High St Kensington area, and work is on the Strand so anything in those areas would be great.

Any advice appreciated!