I have always had Goodyear NCT5 Runflats on my 5 Series, just because they were the tyres that came with it when I brought the car, and was generally pleased with them overall for the cost, but recently they have been on back order and I have been unable to get any. After researching on the net I decided to go with either the Pirelli P Series Run Flat tyre, or the Continental Sport Contact Run Flat. I went with the Continental as they got better praise, and I'm glad I did. I have only had them a short while but I noticed a difference immediately the moment I drove away from the tyre shop. The road noise is virtually non existent, the bumps in the road don’t seem so harsh when you ride over them, unlike the Goodyear if you hit the smallest pot hole it was like you were crashing through a wall. The Continental give a much smoother ride, and grip better than the Goodyear in the wet and dry.
I have not had the tyres on long enough to comment on their longevity, but based on the short time I have been using them I would definitely buy them again, only downside of course is the cost, they are a more expensive tyre than the Pirelli and what the Goodyear were, but then again, regardless of who makes them, Run Flat Tyres aren’t cheap.