Eyepiece::Astromania or Meoptex
7-21mm is a pretty common zoom eyepiece option, available from the companies you identified as well as others like SVBONY and Orion. (8-24mm is another popular option).
Doing a quick search for the Meoptex, it appears to have the same apparent FOV's as the Astromania, as well as the same eye relief.  It's not impossible that they are the same design, repackaged for another company.
Another feature to look for in telescope eyepieces is &quot;fully-multi coated&quot; which will minimize reflections and stray light (Astromania, Orion, and SVBONY list this feature, but Meoptex does not).
IN my limited experience with telescopes, it generally holds true that the more expensive options have better performance, but your total performance will be limited by your poorest component.  (A \$200 eyepiece won't make a $25 telescope any better)
You can also look for used eyepieces, advice, and reviews on cloudynights.com.