Ostrich and Buffalo burgers are still superior by a wide margin. Ostriches are very lean and are not really commercialized. Buffalos, by US law, cannot be fed any antibiotics or hormones and are required to be grazed, not fed grain. Plenty of reputable firms selling both, no need to shop on Ebay.
Buffalo are the way to go, delicious and a healthy alternative. I also like Dr Preagers kosher california veggie burger, blows away all those other veggie burgers. I buy it at costco good value too, a dozen for about $15. Substantial things with large veggie bits in them. I thrown them on the grill with the buffalo burgers and put both on the bun. Meat and veg in one burger and so good.