Power champ or opta-champ

Got a few kids that have been wanting to feed either or of these products. I don't  know much about them I know what they are suppose to do but have never used them always used some stuff that sun glow use to make. Just need someone to shed some light on it for me and maybe what product works best. or is there something else out there that works best. I know there is a big debate on beta antagonist in market animals and I have my own opinion and this is not what this post is about. Just wondering about the products and people opinions of what works best or if there might be something out there that is better.

Thanks in advance

I'm not certain if one works better than the other but IMO the steers need to be sound as heck and nice and fat before they are a candidate.  Also, you have to watch their weight because ADG will increase.  Lastly, read the labels of each, some products have a withdraw and some do not...  G-Luck