1. Ryan Roberts of Roberts Foster - http://robertsfoster.com/. He's a wonderful guy with personalized response to every question you might have. He's knowledgable and can guide you what state and what entity depending upon your situation.
2. Harvard Business Services - https://www.delawareinc.com/ - Reliable and cheap. You can incorporate in as less as $250 and get started in less than a week.
I've personally used both the above entities and recommend them.
All the best!
P.S. I'm not affiliated with any of them.
(By the way, I heard that incorporating in Deleware/Nevada may not be such a great idea if you live in California at least, since they still want taxes from you if you "do business" from there. But I don't really know what "doing business" entails, which is another great reason to find a competent lawyer...)
Just a side note, just register as a LLC in your state of residence, it's cheaper and pretty straightforward to convert to a Delaware C-corp when it comes time to raise funds from VCs.
Reach out to the founders, board members, and CEO/COOs you know and ask them if they have any recommendations. They will almost certainly know someone.