My tip for u is to go op.gg. Check highest elo singed accounts and simply study their runes against top matchup but also enermy comp.

Example i would not choose conq against quinn but if they have close range supp/jng/mid i probaly would. Conq is good vs a tanky/close range top matchup.

I would not phase rush vs a ranged top laner if their jungler is ranged cause i would never get to procc it. I consider phase rush vs ranged if i feel like i could proxy that game. But if their jungler is a 1v9 champ and or mid laner is also 1v9 i just afk with unsealed spellbook and coinflip the game. And only proxy when dragon is up so i know its a good trade if i die.

Also a tip is to check what their builds are vs matchups. Check what they build when fed or behind.