the SIG Tango MSR is pretty good for the money, the Strike Eagle 1-8 is okay too although on above average recoil it might not be the best option. Bushnell has a 1-8 "AR Optic" that is very good for the money asked but has some obvious cost reductions (that make sense) to reach a good price point. some of the Athlon Optics that were circulating the usually suspects are "okay" for a varminting or knock around deer rifle but i'm not sure i would trust one to take a tumble on a rocky slope intact. i usually go with USO/S&B/Trijicon but depending on what you want out of it, they can be very far "too much optic for too much budget".
Eotech Vudu is excellent but very expensive, the Swampfox Arrowhead is a rebrand and is okay - has bad edge distortion at high magnification like the Athlon, Leupold has the CQBSS which falls between the Trijicon and Eotech - excellent quality, expensive, and for the Mk 8 specifically is kind of old tech.
you might want to really outline your requirements and see if the thermal optic you want to use has a specific height over bore or mount or something to help narrow things down as well as the environment you're shooting in, the ammo you are using and if you need specific features like low light lens coatings, 1/2 or 1/4 turret adjustments, a particular reticle or eye relief for the ocular lens, options for a specific mount, et c. there's a lot of things out there.
if in doubt and you're an "average shooter" then it's hard to go wrong with the Strike Eagle or Primary Arms or SIG MSR.