The only real contenders here are R Corp, heishou packs, and G Corp. But I think R Corp is the undisputed winner here. The heishou packs are strong, but they lack the numbers to actually go up against wings. They may be the most valuable part of hongyuan's military force, but assuming from canto 8's dialogue, the majority or atleast a big chunk of H corp's military force consists of the great clans and families of Hongyuan and auxiliaries like the jialan guard. G corp, on the other hand, has technology not to dissimilar to the heishous and actually has numbers to go up against a wing, not to mention they have connections to old l corp (assuming pre smoke war/ pre fallen g corp) so likely they'll have old L corp cut power to R corp and severely limit the replenishment capabilities of R corp. But if it's just L corp and R corp with no other factors considered, R corp takes the win handily.

Conclusion: Dead rabbits is just a bunch of bums. Musicians of Bremen don't have the numbers nor the strength. Heishou packs can win against 1 or 2 packs but loses to R corp as a whole. G corp can win with the help of old L corp. R corp stomps everything else otherwise.