I never cut down to one rooster if possible due to accidents, predation, or illness.. I understand feeding an extra mouth isn't an option for everyone though. In truth 8 hens is too many for an individual rooster to attend
properly in more natural settings. How confined (or free) is your flock?
Cockerels (roosters under a year old), don't count, haven't proven themselves, and may still change their attitude once the whole gig is his own. They usually weed themselves out. As far as I can tell we are actually talking about pullets and cockerels here??
Ratios matter some but attitude of individuals matters more.. I've successfully kept two stags over just 4 ladies withOUT broken saddles, bare backs, etc. I wouldn't recommend it most of the time, BUT it did happen.
A single rooster may still over mate his favored hen despite having plenty too choose from.
Aggression towards dogs or cats is never tolerated here.. while some roosters may successfully fend off a predator.. most the time they're just front line sacrifices or part of the fallout.. In other words NO match for most the predators my flock will ever face.
My personal dogs won't let a stray into our (fenced but only 4 feet high) pasture and will be more equally matched should one try. A balanced cock should be able to stand watch and discern threat from non threat without having to go after them from across the way. Able to watch them walk by or even run by.. maybe voice a little protest but without attacking for no reason. I think you made the right choice but am very sorry for your loss and experience.
I will note that when my head is screwed on right.. those birds are also harvested if possible for the table or (other pets) instead of wasted/composted.. doesn't really feel any better but it's still good to remember we have options.
Beyond that, the purpose of keeping the rooster would effect determinations.. Is it a certain breed with
standards of perfection to meet (which you also care about and are breeding towards), Or if there's no SOP then who contributes most to egg production verses meat production.. egg color contribution.. definitely who the ladies like but also which one I like looking at.
If not breeding for sustainability of some sort.. then eat em both and let the ladies live in peace..

a head hen will still make predator calls and such. A GOOD rooster is worth his weight in gold, both to the keeper and the flock ladies.. on a deeper level than predator protections.. and I'm not trying to discount that.. they are few and far between in MY experience.. it's worth continuing though.. if at first you don't succeed. Try, try again!
Post pics and descriptions of different behaviors and or characteristics that maybe you wanna discuss about your boys.