I absolutely worship Pink Floyd, and DSOTM - Animals is probably my favorite three album stretch by any band. However, Pink Floyd's consistency (or lack thereof) is why I can't pick them over Rush. While my favorite period of Rush was the late 70's early 80's, there's no period of their career I don't like and the last 3 albums have been great. They just released Clockwork Angels in 2012, and it's their best album since Moving Pictures, which is 30 years old.
Rush has continued to improve and write NEW MUSIC, and although AMLOR and Division Bell were good albums, PF hasn't released a great album since Animals (IMO). The Wall and Final Cut are great albums, but those are more Roger Water's solo albums than they are PF albums. I worship David Gilmour, but it's obvious on those albums (not counting C. Numb, RLH) that he was marginalized.
Rush is practically the only band of my favorite progressive bands from the 70's that continues to make new, good music and continues to tour. And their live shows are the best in the business from my perspective, and I see lots of shows. If Pink Floyd was still a cohesive band making new albums and touring, then I have a feeling they would get the nod, but picking them now would be a sentimental choice more than a real one for me.