Press the Attack > Lethal Tempo

Still.

There still isn't a single champ where Lethal Tempo is going to be desirable over Press the Attack. Because they both afford more damage while Press the Attack has a bunch of extra perks. No cooldown, some nice up front burst damage, and a damage amp your whole team can benefit from. And to add insult to injury, they both boost your DPS by about the same amount when all is said and done.

These two Keystones need to have distinctive niches to fill. They're simply too similar. Just buffing one and nerfing the other will result in players juggling whichever option is more OP at the moment. Press the Attack is clearly the team fighting option. Extra damage against an exposed foe is amazing. So Lethal Tempo should be giving some other benefit aside from just more basic attack damage against champs

Rather than cooldowns and spooling times, Lethal Tempo now ramps up to its full attack speed boost after three basic attacks against a champion, a tower, or an epic monster. Stacks drop off one at a time per two seconds (four seconds for melee). This would cement Lethal Tempo as the objective focused option, giving it a clear advantage over Press the Attack when it's being used in its niche. Obviously this might require tweaking the exact attack speed boost Lethal Tempo gives on live, but I think giving the keystones more distinction would be well worth it.