had both, well not a normal powered s anyway. 182 is faster slightly than a standard s, but the interior and general envrionment inside the mini is wayyyy nicer.
what i liked about my 182 is that you can just bomb about everywhere and it was so much fun. with the mini as it is a wider car, you have to think a bit more, but on the straights my works would just hump my 182. handling is still really good, but the 182 was more predictable.
thing is i am comparing my 182 when i purchased it 6 months old to my mini i purchased 4 years old with 42k on the clock. My 182 felt pants at 53k, the engine was still strong, but the dampers were clearly worn and you used to get mad pitching under braking.
Overall the mini will have more lasting appeal... i didnt get bored of my clio for the first 2 years, but into the 3rd year it got a bit boring as the car just felt cheap and it wasnt worth tuning it as it was already not worth much and tuning it would have meant it would have lost even more value.
once you are happy with your mini, you can just get a 15% reduction pulley, and exhaust and you will be near 180-190 hp and the car will definately feel more alive.
I would say mini for longevity as they have aged a lot better and will last you longer. I wouldnt really contemplate purchasing a 4-5 year old 182 now as they will feel pretty tired.