“the AH was a posek while the MB is at times more theoretical.”
The difference is like the difference between Rav Moshe and Rav Soloveitchik. R’Epstein and R’Moshe were poseks; The Chafetz Chaim and The Rav were rosh yeshivas. Rav Henkin z’tz’l also held that we should prefer the Aruch HaShulchan.
“he claims that the Rema is wrong”
The Aruch HaShulchan is far from unique in saying that the Rema should not be followed; for example the Vilna Gaon rules contrary to the Rema on a regular basis.
“he loves the yerushalmi for some reason”
Not clear what the problem with the Yerushalmi is, or why we would not follow it, especially when the psak of the Bavli is unclear. But we clearly do not do regularly follow the Yerushalmi.