What Orbi will work best for me?

The eero 6e is a pretty solid system. Like FURRYe38 says, you'd have to upgrade to the 8 or 9 series to get faster speeds and thats quite a price increase for not much extra speed. 

Instead of upgrading, see about adding an outdoor extender to your current setup. there aren't any current ones from eero or Orbi currently so you could probably just use a standard wifi extender thats outdoor rated and put it halfway between where you need coverage and the house. that might do the trick but you'd have to check with eero. 

In terms of speed, it usually isn't the router that is bottlenecking your speed but the device you use (phone/tablet/etc). And most devices don't need more than the 200mbps your hitting. Reason I say that is you can stream 4k with only 25-40mbps. So unless you're uploading a load of data over wifi, you're current speeds should suffice for what you're doing.