They are all good teams. Not sure how you pick a preferred opponent among them.
Rays: Snell, Glasnow, Morton + 11th best position player assortment in MLB + #1 bullpen (well rounded opponent)
Indians: Bieber, Carrasco, Plesac, Civale + #3 bullpen + 17th position player assortment (great pitching)
White Sox: Giolito, Keuchel, Dunning + #9 bullpen + #2 position player assortment (great lineup and two good SP)
Twins: Maeda, Berrios, Pineda, Hill + #5 bullpen + #7 position player assortment (well rounded opponent)
Toronto is #16 position player assortment, #12 bullpen, + Ryu and crap. Clear underdog against any of them. Need to rely on players who did not really help them much during the regular season (as far as total fWAR is concerned) like Pearson, Ray, Kirk, Villar, Stripling, Shoemaker, and Vlad.