Based of what we've seen of both, I'd pick Bruno. That could change in the future if I see that Povetkin's got a spectacular chin or recuperative powers, but he hasn't faced the kind of puncher or taken the kinds of shots to say whether he's got those qualities yet.
So the british commentators said one of the most popular british fighters ever (Bruno) would beat the russian, and that proves what? I think the russian commentators disagree with that. Imo Povetkin is too fast, too clever, too busy and has too much stamina for Bruno. Povetkin would have figured Bruno out after one or two rounds and win a comfortable points decision.
Bruno would have to KO Povetkin early (inside of 4 rounds) to win and I don't think there is better than a 10% chance of that happening. Povetkin is much busier, has better stamina, and is the boxer with better skills. Bruno hit very hard but didn't have superior hand speed to go with it which would make it difficult for him to catch Povetkin flush. I think Povetkins chin would hold up to the punches he did take until Bruno slowed down and he took control of the fight. I would take Povetkin by UD or late TKO.
Povetkin has one of the most prestigious amateur hw record in boxing history. Povetkin doesn't look anything special... But he's extremely endurant & has a very impressive workrate...so much so that it compensates for his lack of ko power.
That's a big factor in it though, because one of the things Povetkin does extremely well is wear out his opponents. I just haven't seen enough to know either way whether or not AP's got the chin or recovery to last that long to do it.