On the surface, Martha Coakley(D) seems better on the issues than Charlie Baker(R), but it's kind of hard to tell what their differences really are. Neither has a solid record on a broad range of governing and policy, as they would if they'd been a mayor or legislator.
Charlie Baker spent most of his time in the corporate world, and he talks moderate but reminds me a lot of Scott Brown and Mitt Romney. We certainly have a recent pattern of Republicans much like him talking moderate to get elected and then showing their right wing colors once they're in higher office.
[On the issues...]On the other hand, Martha Coakley's record is entirely on the Attorney General side of things (before that, she was Middlesex DA). While she's been good on equal rights for women and LGBT people, she's really sucked on many of the core issues that the Attorney General's office exists for. Weak on justice and on criminal justice reform, pro-Patriot Act, pro-drug war, pro-surveillance, anti-rights for the accused, pro-keeping innocent people in prison.
How would these two govern when it comes to the economy, environment, wages, health care, crime, transportation, infrastructure, education, ... mostly we just have to take their word. Coakley's need to maintain relationships with Democratic groups would probably keep her on the better side of most of these, but I don't know what she'd actually fight for or initiate. Baker, I fear, would pull a Romney.
On womens' and lgbt and gender equality and reproductive choice and related issues, I think we've done a great job in the Massachusetts progressive movement over the past decade in changing the legislature such that we can get much of what we want regardless of governor. When it comes to things like, say, repairing and expanding public transit, or reforming taxes to make them fairer and better finance the state, our legislature is still the main stumbling block. We need a Governor like Deval Patrick to really push them, still not get most of what he wants, but make some progress. Baker likely won't even support this kind of progress, but I don't expect Coakley to push for it, so the end result could be similar.
Coakley, on the other hand, will probably promote casinos while holding back medical marijuana and trying to prevent decriminalization, and will be a drag on any efforts for criminal justice reform if we get real leadership on that from other quarters (like certain state senators). Health care financing changes, especially single payer, will come from the legislature and be resisted by either of these governors.
To sum up, on balance I think Coakley will probably be somewhat better but it's hard to tell. Balance that out with the fact that she's been awful on some of the main issues she's actually been responsible for, while showing herself repeatedly willing to promote gross injustice on an individual level.
Another factor I think is important: Either one of them, if elected, will be very vulnerable and likely to be replaced in the next election.
Charlie Baker: He's a Republican in a Democratic-leaning state, with various positions opposed by majorities here. He can win against a bad candidate like Coakley, but his chances against a good Democrat would be low, even as an incumbent. Not to mention the rather consistent pattern of Republican Governors in Massachusetts either not running for re-election, or leaving partway through a term. We've had four Republican Governors in my time in Massachusetts, and every one of them has done one or the other.
So, Charlie Baker represents a great opportunity to get a really good Democrat in as Governor in four years. If Coakley loses this time she's unlikely to win the nomination next time even if she runs, and we can nominate someone much better and beat Baker. On the other hand, if Coakley wins this time, we probably won't have a Democratic primary contest in four years, she will be renominated, and will be vulnerable to losing to another Republican. Will that one be better or worse than Baker? It's a risk.
On yet another hand, our Republican Governors' pattern of leaving partway through their terms means we frequently end up with the Lieutenant Governor in charge. Baker's running mate, Karyn Polito, really is a right wing extremist. She also was a leader in trying to ban gay marriage, voted against the transgender equal rights bill, filed a complaint against the Registry of Motor Vehicles when they started allowing people to change their sex designation on their drivers' licenses, co-sponsored a bill to require schools to notify parents if any mention of anything LGBT-related would be made in school... she's the kind of awful that usually gets sidelined in Massachusetts.
If it weren't for Karyn Polito I think I'd be leaning a little towards hoping Baker wins, and looking forward to the opportunity to elect someone good in 2018. She tips the scale for me, and I reluctantly and ambivalently recommend voting for Coakley, to avoid the high risk of Karyn Polito becoming Governor if Baker wins and uses it as a springboard to run for President, or just plain leaves.