Hero line up advice and prioritization

Hi guys, just been playing for 6 days, still f2p. I read the tips section and was planning on building up captain, Levi and Denali and my first 3 star base Akasha to make a decent team.

However, my guaranteed 3⭐️ summon gave me Athena, then these two days were kinda crazy, with elite scrolls netting me Octavia and Diana.

With these heroes, I'm wondering who should I prioritize to 5 first or transcend? And which combination of heroes would be best?
Thanks in advance!