I think the Cubs/Nats series is a tossup, and I will favor the winner in the NLCS.
That said, I think the Tribe are heavy favorites right now to win it all. They look like the best team in the last 5-10 years. But baseball is weird. The best team doesn't always win. It will be fun seeing how it all plays out.
FWIW 538's ELO rankings put the top teams in the last decade in the following order...
2009 Yankees (33 all time) - 103 wins, WS title
2007 Red Sox (66 all time) - 96 wins, WS title
2016 Cubs (70 all time) - 103 wins, WS title
Right now the Indians ended up with 102 wins. I think they are definitely up there with some of the best teams we have seen in recent history. For my money right now I think it is probably last year's Cubs team, the wire to wire dominance was just so impressive. Even if the Indians win it this year it would be tough to unseat them in my mind, but it also depends on how they do it. If they march through the playoffs they definitely have to be considered.