Care to explain your thinking?
Bullock wouldn't have the same appeal as Sanders in any of the green states except for MT and mayyybe WV, and Booker is a much better candidate than Clinton (though that's not saying much) - higher AA turnout alone should be enough for him to win in MI, and I highly doubt he'd do worse than Clinton among White voters in the Midwest. Plus, it's not as if Bullock is some populist hero and Booker is just the awful neoliberal - it's not as simple as this forum wants you to believe.
But yeah, I know you want 2020 to be a Phil Scott/John Kasich vs. John Bel Edwards/Steve Bullock race. 
I don't see how you get Booker as being a strong candidate. Hillary was able to dominate the early primaries largely on the back of name recognition. She still had allies amongst the older WWC Dems. I thinks it's extremely important to examine the Obama '08 and Clinton '16 primary coalitions very carefully. Booker will probably do well with black voters, but it remains to be seen how he appeals to the growing progressive base of the party. He actually suffers a lot of similar flaws tof Clinton. He's seen by large portion of the base as corrupt/shady, and he's bound to do poorly with working class whites. If anything he's a weaker candidate than Clinton. Clinton was the first lady of a beloved president. Booker's a nobody outside of political circles. I especially think you underestimate Bullock's appeal with the Sanders base. To the Sander's base authenticity is key, and Bullock is extremely authentic. He also has progressive credentials. He'll use that as leverage to paint Booker as the big money "Washington" candidate. He comes across as much more palatable to older white voters as well though. He's not an old socialist Jew so I think that'll help him with those voters.
