Both would be the best playit's a toughie. Olam brings experience and an attitude to training and playing you can't coach. that will rub off on the playing group and help with the rebuild. Niu is a better buy in terms of age and upside.
personally I'd love both, but if Olam comes and finds form then I think we won't be worrying too much.
Both walk into our backline
Olam, experience and class.
Niu, at his best... very flashy and explosive.
improve our backline so dramatically.
Staines and Lobb on the wings.
I really like that.