well, i start to see a big difference from about 5%+ when trading in lane.
you will notice this ESPECIALLY in jungle when you try multiple setups for clearing and you realize that a little bit attackspeed can save you hundreds of health. ofcourse attack speed doesnt mega-scale on your flat auto attack damage without any added effects, but many champions have some sort of on-hit effects inbuilt so that an extra bit of attackspeed scales with that too and has insane effects.
for example, my main shyvana has three on-hit effects, one on each ability.
her Q reduces the cooldown of that spell by 0.5 on hit, her W deals 20% of its damage on hit and her E deals 2,5% max enemy health on hit, this means AD runes on her is completely wasting her strength while going attackspeed scales absurdly.
many champions have that, and coming back to the tryndamere situation: he ACTUALLY scales on attackspeed with his passive too, because he gains fury for every auto attack and crit, not for how strong his auto attack is. this means, with attackspeed, you build fury alot quicker too, which, in lane, leads to better all-ins and trades and in jungle especially leads to alot more sustain.
attackspeed is just WAY WAY WAY better in all scenarios on all champions EXCEPT if they have massive AD scaling on abilities (like pantheon, zed, renekton etc) but it has to be kinda big scaling on multiple abilities. a good example is the BOTRK. almost all champions that this item is built on have bad or no AD scaling on their abilities but synergize good with fast auto attacks anyways.