Like others said always clay. It takes time, but it leaves the surface glass smooth. If you polish before claying it will leave maring and pigtails everywhere and it will look worst than before.
AIO work well on daily drivers and truly cars with soft paint. I did a 94 mercedes with xmt360 and it looked almost perfect. I have worked on a 2000 pontiac grand prix before and it didn't have soft paint. I had to use megs ultimate compound and m205. Other cars I've tried xmt360 and barely noticed a difference, probably because of the paint hardness.
If you look on the cut chart xmt360 is a 2/10. m205 is a 4. You really won't get great results with xmt360, but it will make the car look better in a short amount of time. xmt360 protect last amount a month, maybe 2 if its garaged. Atleast thats my experience. Some daily drivers I do xmt 360 and put a filler wax on top of it(takes another 15mins to add a layer of wax and buff off).