As most here are MINI/driving-fanatics/enthusiasts I decided to give some highly rated tires a go:
Yokohama A052 grip the best in corners (maybe 5% or so improvement) are loud in certain situations and bit choppy too.
Mich Pilot Super Sports are more touring type, soft quiet but the soft sidewall caused interference with the struts & rear control arms.
P7 (factory) tends to have a plastic-ey feel, loose grip easy, loud, choppy-est of the bunch but no sidewall deflection.
IMO neither are worth the upgrade as I don't race the car. For future ref. I wouldn't purchase tires until my factory's wear out.

I hated the factory P7s ... poor grip and generally poor performance all around.

I replaced them with a set of Continental ExtremeContact Sport. What a difference, responsive, super grip, smooth, quiet, and lasted 33,000 miles. They transformed the car. Getting rid of the P7s was the best thing I did to the car.

The Yoko's rubbed the struts, Tuesday the P7's are going back on, costly lesson. The tolerance on these cars is such that only a MINI approved tire is guaranteed to fit?

What size A052 and what width
and offset wheel?

Factory 205/45-17 size and factory 54mm offset wheels. The P7's have a narrower tread/shoulder than the other tires out there. My guess is that most people don't even realize the tire rubs/interferes or they don't care.

Could add a 5mm spacer to bring the
ET down to 49mm.
That would clear the strut and still
leave plenty of room at the fender.

I was thinking 3mm spacers because you should be able to find them at a local auto parts store relatively cheap and would not need longer lug studs. Have not bought any in a long time but they make a universal bolt pattern that fits almost all cars. You really will like the Yoks.

Not the best spacer but functional. If it works and you like the tires , spend the extra money and get hubcentric spacers with longer lug studs and push the wheel and tire closer to the fenders for a nice look.