Replaced all the 205/45/17 Pirelli Runflat tyres on my MINI with Goodyear Eagle F1 GSD3 215/40/17 non runflats (same overall diameter, slightly wider) a while back.
Pros: cheaper than runflats, much smoother ride and far better grip and handling than the runflats with their stiff sidewalls. Also no tram-lining.
Cons: You need to fit a space-saver spare (Cooper or One) or to carry a can of puncture repair from Halfords (Cooper S).
I think the latest generation runflat tyres have however improved......not sure about the 'budget' brands though?