The fit needs to be entirely personal. Consider for a moment that the amount of money, or value of services, invested is insignificant relative to the real needs of the business. In most cases, the investment of any kind, by a true incubator, is little more than a token of recognition to help cover some costs. Think about many of the perspectives shared by Peter Drucker (famed Economist), or if you need someone more recent, Tony Hsieh: Culture is the only thing that matters.

Incubators are generally expected to accelerate the development of startup and fledgling companies by providing entrepreneurs with targeted resources and services (via http://seobrien.com/evolve-way-work-role-coworking-spaces-incubators-accelerators). So what you have to ask is what you need; recognizing that the equity/cash transaction is not just comparable from one to the other but likely rather irrelevant.

You should be looking at:

- The principal mentor they provide (they are providing one right?)
- The services available and their cost/benefit relative to acquiring those services elsewhere
- Their network, what you need of that network, and how they will ensure (no, guarantee) you benefit from that network. Said network should include professionals you might need to leverage to round out your team - as well as media, investor, and partner opportunities
- Value of office, meeting, and event space available at no-low cost
- Their ability to help you find/secure working or seed capital

Weigh each of those considerations across each of the incubators at your door and then throw all that away and revisit the personal question of cultural fit. Do you WANT to work with these people? Will you enjoy working with them? The value you might derive from an incubator is entirely dependent on the contribution you'll make to what they can provide. If you aren't in sync with them, you'll miss out on some of the value you can bring to your venture; and frankly, they'll have wasted their time with you - don't let that happen. Make a decision based on exactly the same qualifications you had in finding a partner/co-founder: would you put your career in the hands of this organization and give the relationship your all to see it work? If not, if you're making your decision based on their track record, reputation, media attention, quantitative values (e.g. cash), or heck, even those benefits they SHOULD be providing, you're evaluating the wrong things and will likely waste your time and theirs.