Both items you mention are oxidizers and will do the job. bleach is cheap while peroxide is not so much and I keep in mind that bleach has the chlorine that we normally find in tap water as it is deemed to be the most cost effective. The difference between bleach and tap water is how much we dilute the chlorine, so that leaves me using it for almost all my cleaning. The tricky part often comes in how much we want to dilute it as that depends on how much grunge we have to clean up! For a used tank where I don't know what has been in it, I often just go for pretty light like a half cup in a 55 and let it all set overnight, but then I also bought a house with tank that had a pleco carcass rotting away and I used half a jug on that one! So it takes a bit of guessing how much is enough without wasting the bleach?
I often let it soak for overnight, or until I get time to get back to the job but once the soak is done, it is treated the same in almost all cases. I drain the bleach water, watching where I put it. Not on my clothing, nor in the yard to kill the grass? Then I rinse the stuff to further dilute any mix hanging around and let it dry totally and as the gassing off is done, I no longer smell the bleach and treat the tank as I would a new one that I felt good about it being safe.
I do all the parts like the filter body, decor, and such at the same time, except I don't run any soft media that I want to keep through a really strong soak and I do watch for things which the bleach may take the color out of like rocks which I might want for the nice coloring as it may change when bleached.
Main item of worry? Have you seen the tie-dyed jeans with holes in them? If you don't want your jeans like that, keep the bleach off! Cheap, simple, no scent, no color bleach is good for this job.