Since its all just opinions....
I would only use Meguiars No7 polish if you are doing old style paint (original, laquer, very old single repaints). Base/clears really don't get the benefit of its oiling effects. If you have old paint use No7 and leave it on overnight, heavy, then buff off by hand. Literally put it on thick and let it soak in. Don't follow the directions. cool, inside, overnight.
Newer paints (single stage and base clears) that you just want to make look better, then buy Meguiars 105 and 205 ultra fine cut polish. Use a DA polisher from (gasp) harbor freight if you are cheap and get a good quality pad. Follow the instructions doing the 105 first then the 205 and the results are pretty good even if you are a newbie. Of course, go slow and careful on the edges even with a DA, but the combination of both work surprisingly well.
I Highly recommend not touching a rotary buffer if you are new to them.
Good luck,
RGAZ