What Extender to purchase

As cheap as those extenders are, I think you'd be better off to invest slightly more. That R6080 is old/slow and could be part of your bottleneck as it isn't even gigabit. You're hitting 94 Mbps so its indicating your speed is bottlenecking there. If you're ISP is giving you 300mbps, but the router is limiting it to 100, you're starting at a lower point. 

If it was me and I was on a limited budget? I'd check your local facebook for a used orbi setup. I"d look for the 20 through 50 series (avoid the 10). They can be picked up pretty cheap used, would give you a gigabit router and then a satellite with a dedicated backhaul. I've seen them used in my area (Minneapolis) for that $25-60 depending on the series. It costs a little more and they're used, but you'll get better performance than a single/dual band extender. Plus you'll upgrade the router and have a higher starting point. 

Again, that's just me.