How to reduce spectral leakage?
If you want to have the best SNR possible, you put a null on the signal that is leaking it's energy.  In order to do that, you either have to know the location of the interferer or use an adaptive filtering scheme.  

If you want to stick with a fixed window, the Taylor window isn't a bad choice,  It's like a Chebyshev and rolls off further out.

A. Villeneuve, "Taylor patterns for discrete arrays," in IEEE Transactions on Antennas and Propagation, vol. 32, no. 10, pp. 1089-1093, October 1984.