Shakir is a good receiver and he is an ascending player. But he is an inside slot guy. Yes he can play outside and he does get used that way, but he is most dangerous in the slot and the middle of the field.
That limits his ceiling, honestly. Especially with the Bills, who do not have a high volume passing offense. Targets and touches are limited.
He is young and ascending, though, so I think that gives him a bump and I'd put him ranked in the mid 20's somewhere. There would be more productive receivers below him in the ranking, but they are guys on the descent or who are productive because of their situation rather than raw ability.