Personally I find Meguiar's #7 easier to work with.
They are both basically designed for the same thing. Fill in swirls and follow with a carnauba wax.
The 3M imperial Hand Glaze was designed for hand use. If you don't apply it nice and evenly you are stuck with a streaky looking surface. My 3M IHG is untouched. My Meguiars #7 is half way through.
Both can be used with PC, BUT 3M IHG is not meant for use with PC, I think past Autopia member "moe" wrote a nice post on 3M IHG usage by PC.
The popular combo in the older days of autopia was 3M IHG/Blitz. I settled upon Meguiar's #7/#26. Sooner upgrading to #7/Blitz. Then came everything else (P21S, Blackfire, Klasse, Zaino, Platinum, etc. etc.)
Jason