Every browser alternatives you can reasonably choose today is going to be either Blink (Chromium-based) or Gecko (Firefox-based). And then you have WebKit (Safari).
Ladybird, Flow and Dillo are really the only true alternative browsers in active development other than a few others running on niche operating systems (to which I'm throwing in all of the DOS browsers...).
Every browser alternatives you can reasonably choose today is going to be either Blink (Chromium-based) or Gecko (Firefox-based). And then you have WebKit (Safari).
Ladybird, Flow and Dillo are really the only true alternative browsers in active development other than a few others running on niche operating systems (to which I'm throwing in all of the DOS browsers...).