I see three types of strikers
i) Powerhouses to hold up the ball. Current world class strikers: Zlatan, Drogba (in his days). Potential for us: Mandzukic, Lukaku, Balotelli
ii) Someone with low gravity, high work rate and can create something from nothing. Current world class strikers: Aguero and Suarez. Potenial for us: Alexis Sanches and Tevez (old)
iii) Good finishers, clever runs and quick(ish) but don't create things out of nothing. Current world class strikers: Cavani, Costa, Benzema. Potential for us: Benzema , Walcott (did a great game before he got injured).
I would want us to go away from the Giroud type of striker - at least for plan A. Giroud should be plan B when we play against a physial side. Otherwise I prefer option (ii) but realistically speaking there is not many of those players so category (i) and (iii) are easier to find.