The Walther-made Umarex MP5's have outstanding cosmetics. The MP44/22 is certainly kewl and builds muscle while you shoot it.
Mags are not easily found for either these days. It becomes a coin flip.
Maybe also consider;
Umarex is based in Free America, Arkansas.
American Tactical is in NY.
Posts on ARFCOM make it seem that unlike Magpul, ATI is reluctant to swat back at NY gov't for what they did to NY'rs.
Maybe don't support NY based business?
In a victim nation, a classroom full of dead children is morally superior to a teacher holding a smoking gun knowing she just protected her students.