I personally think out of last years three (Ings, Kane and himself), Berahino was is by far and away the better footballer and prospect. Quick, technically sound. Strong. Great in the air. Played the lone role real well when asked for West Brom, holding it up well and winning it which for a young kid is a heck of an ask at any level, never mind the BPL. Although he didn't score as many as the other 2, the verity in his goals was fantastic too.
Yeah, he's by no means the finished article. But put that potential alongside better players and with better coaching to mould him to what you want and someone could have a real gem on their hands.
For the here and now obviously you need proven, quality experience behind Rooney. But if money is 'no object' as we're lead to believe, dropping the £20 million on that kid West Brom want would be a great calculated investment for United or any other top club IMHO.