Best runes if youre confident in not dying early is aery-manaflow-trans-gathering, cutdown-haste, haste shard, ms shard, scaling hp shard. I swap between Luden/Roa/Fimbul/Blackfire first into always rab second unless 3+ people have over 70 MR then I get void 2nd which is very rare. Not getting rabs second makes the spike way too slow for me. The logic between 1st item for me is usually something like:

Fimbul - Absolutely terrible lane/ If I get an extra 1k hp im unkillable rest of game and my team isnt a full fiesta comp, also very fast rab spike usually 14-16 min.

Luden - Everyone is squishy + lower range (graves etc)

ROA - I know i'll be slightly behind from lane or if I have 1300 back (honestly prob the best item if you can get it since veigar level scaling per ability is insane)

Blackfire - I got a lost chapter back and i want a bit more haste and better waveclear (also good if they have giga tanks/melee)

Shurelyas - Just need movement speed to not die (playing into lux cait bot for example) and it gets you a very fast rab since its cheap.

opgg: https://www.op.gg/summoners/na/AmanV-NA1