Need Some Thoughts

so .. i have exactly 8 somewhat decent rune for bombers. my question is, do i need to go all-out, make one super bomber and one so-so bomber, or have 2 decent bomber , but not super bomber? something like 4 rune each , or 6 rune for one , and 2 + 4 so-so rune for the other?

my bomber is jojo and taurus

thanks in advance :)