if he joins, frontcourt would be loaded with davis, amir, bargnani, alabi. Not to mention FAs such as dorsey and evans (and i want evans back as a mentor, only at a cheap price though and i wouldnt mind dorsey either)
When you draft a guy at #5, the chances are that you want to play him A LOT, and that's not gonna happen because 85-90% of the playing time in the frontcourt are occupied by bargnani, amir, and davis.
Therefore at this point, the raptors should be and better be leaning forward to draft a PG and SF, therefore the candidates (to me) are only Knight, Walker, and Leonard in that order.
Knight has the highest potential, Walker is the best Leader in the draft, and Leonard's the best defended in the draft, can't go wrong with any of these 3
Some might put Kanter on that list too but i am not too sold on that guy, because I am one of the few guys who still have faith in bargnani.