Looking at the standard potentials table it shows:
As the table shows reduction potential, F2 reduces to F- with the highest potential in the table (2.89 V)
Flipping around the equation gives F- oxidises to F2 which gives it a very low reduction potential (-2.89 V)
As we know an oxidant (oxidising agent) is something that accepts an electron and reduces, so therefore F2 would be the strongest oxidant.