Difftastic only diffs code, which is only 2/3 of all diffs.
When only measured on stuff difftastic supports:
Difftastic is perfect on 64% of diffs and near-perfect on 17% more.
Omnidiff is perfect on 90% of diffs and near-perfect on 5% more.
Speed is
p50 - 35ms difftastic vs 4ms OmniDiff p99 - 637ms vs 420ms
Difftastic is MIT vs AGPL.
Care to elaborate? What does Omnidiff offer for non-code files?
Note that you do need a terminal with image support, like kitty, alacritty.
If you do not have image support, it does its best with image2ascii, but it is obviously severely limited.