We went with a broker based in DC, Joshua Lavine, for health insurance, since that's where we [eventually learned that] we needed to base our plans from. Great experience (well, the DC small business health exchange is a separate sad story.) Health insurance is so complicated and state-specific you really want someone knowledgable.

We went with Captain401 (a YC startup) because we needed a fast turnaround and they had amazing service. Too early to render judgement otherwise. OctaveWealth is another seemingly competent YC 401k startup. If you're not in a rush and don't want to trust a startup with your company's 401k plan (though assets are safe regardless), Vanguard is great, and would have been our backup option.