Yes, Tri-Force wasn't always the best choice for Darius until about Season 9-10 due to various item changes and buffs/nerfs to Darius. Since Season 11 Stridebreaker has superseded it as a better choice all around.

Stridebreaker and Tri-Force have all of the same base stats but they are weighted differently. Stridebreaker has more 100 HP and 20 more Attack Damage while Tri-Force has 20% more attack speed. A max stack Tri-Force passive does give more attack damage but only as you land more Auto Attacks on enemy Champions and get you 50 total AD, only 5 more AD than Stridebreaker has already. The 20 flat AD on Stridebreaker is much better from the outset and more beneficial than the extra 5 AD you gain from a max stack Tri-Force. And by then once you have 5 stacks on a champion as you'll already have your Noxian Might passive bonus AD as well so the 5 AD is negligible.

They do both have the same passive of granting move speed BUT Tri-Force only grants move speed when hitting a basic attack while Stridebreaker gives move speed on ANY physical damage dealt, including it's own active that deals damage.

Additionally the active on Stridebreaker is more beneficial as it is a small dash to close any gaps and also slows the enemy allowing you better time to get into them. Tri-Force has no such active. Tri-Force does have the Sheen passive dealing 200% basic attack damage after an ability.

It comes down to preference really but more often than not Stridebreaker wins out due to its utility, more HP and flat AD.

ALSO while Tri-Force gives you 10% attack speed on any legendary, Stridebreaker instead gives you +3% Move Speed which is way more beneficial in being mobile, catching and running down enemy champs. Move Speed is vital on Darius as he has no gap closers or dashes.

I'm glad you liked it! =)