Williams probably has the best engine. Red Bull probably has the best car. Ferrari probably has the best overall package. McLaren probably has the best drivers.
If it's close between Williams/Red Bull/Ferrari/McLaren it'll depend on small differences that could change depending on the track.
Let's not forget that last year Williams failed to win a race, failed to even compete for a win, and failed to beat Red Bull in the WCC. It wasn't even close. Williams might very well have the second best car-engine combination, but as a team they don't have much to write home about.
Edited by Nonesuch, 01 March 2015 - 14:28.