Definitely 'We Are The Champions', in fact there's one version of 'WATC' has a guitar solo... the one with Robbie Williams.
I always thought that the song would have been much better if it originally included that solo. Of course, with Freddie on lead vocals and without Robbie's whinny voice.
I'm surprised that 'Under Pressure' doesnt have a guitar solo. Although they did record the song in one night, so might not have had time. I wouldnt want it to have a solo though - I think that it's perfect as it is
I've never realised that WATC didn't have a guitar solo, even though I've listened to it so many times!
We Are The Champions should've had a guitar solo. I think it would've sounded better to have one of their most famous songs feature Brian a bit more than it did.