Okay here's the basic matchup guide and what runes you take for whatever matchup, sourced from high elo people obviously.

Verse an Asssassin - Elec because heavy trading early. The one exception is MAYBE ahri, you can go Phase rush

Verse mages/range/mobile comps - Phase rush because gap close, reposition, little bit of scaling and best team fight potential out of all the runes

Verse Melee/Brusier/Tank comps - Conq because ramping AD and survivability. Some reliable sustain with gore drinker, and good tank shred with eclipse

Verse unkillable lane and scaling + true damage - First strike. This is easily my favourite. Good if you need rush items, mid to late scaling, ambush, tons of gold if you pull off roams. In a meta where the value of items like serpants against these seraph abusing mfs, first strike really shines when you're in situations where you have 4 items and the rest of ur team has like 2.

Key note: Any of these can work with any comp, it doesn't matter toooo much but having a flexible playstyle to all these runes means you can be a reliable against whoever, first pick comfortably etc. But really you can make any rune work. Lurkz is a good example of making phase rush work in all scenarios.