Captain + 10 infernus marines vs Biologis + 6 agressors for Blade of Ultramar?

Hey guys! Just painted up my captain today and really wanna get him a bodyguard unit of infernus marines as an escort. Free overwatch on 10d6 shots autohitting sounds wonderful! I was originally planning on having 6 agressors + Biologis in my list. Agressors get the huge volume of fire, are tougher, and are much more potent in melee than infernus. However i lose the free overwatch and overall have a little bit worse shooting.

In blade of Ultramar, which would you guys prefer to take? All in all, im running 12 victrix + 6bgv so my melee is already pretty superb. I'll probably get both of these units eventually but was just wondering which i should prioritize. I will say though, 10 infernus marines is like 40 bucks on ebay and I've already got a painted up captain. 6 agressors + biologis is gonna end up being like 160 dollars. im taking irl cost into account too.