Brixton Academy
A bit of an enormodome, this one. It's also almost certainly gonna be sold out, since the only bands booked in here are those with either a big fan-base or big aspirations. This means that the place will be packed and anyone arriving at a reasonable time (say, 8.30pm) will find that they can squeeze to precisely 1/3 of the way from the back, at which point they will hit a human brick wall and then realise they forgot to get a pint in before embarking on their epic voyage.
Ticket prices at the Academy also seem ridiculously expensive. WeAreLondon's maths aren't great, but have SJM Concerts etc not heard of 'economies of scale'? (i.e: the more people you cram in, with most people miles from the stage without even a large video screen to comfort them, the cheaper the tickets should be).
Never mind though, they could probably charge double and still sell out most gigs. On the plus side, the sloping floor is a bit of a novelty and also helps short-arses see at least something resembling a stage. More negatives though: inadequate bars, overflowing toilets, heavy-handed security, and a nightmare getting home as 3,000-odd people all pile out at once.
Almost enough to make you want to stay at home and watch the gig over the safety of the internet, but of course, not quite.

211 Stockwell Rd SW9
020 7771 2000
Nearest Tube/Rail: Brixton
Note: tickets can be purchased at face value (cash only) at the Shepherds Bush Empire box office.