Solo founders
jmillerinc.com
jmillerinc.com
It's much better to draw inspiration from your users and solid metrics about your business.
I'm not saying drawing inspiration from the users isn't important (ideally, all founders should be doing this anyways), but having another person on the team significantly helps to start.
If an idea is incredibly stupid, but it's your idea, you can easily become deluded into thinking it's actually a great idea. Being able to convince another person that the idea is good is definitely a sign that the idea is good.
It's also a good check on the quality of the team -- if someone is obviously such a screw up that you'd never want to work with him, you wouldn't work with him. Even fairly defective people can notice flaws in others. Therefore, a group of 2+ people probably means the members are at least tolerable.
I wouldn't consider a cofounder unless they could add serious value beyond feedback.
The real question you want to ask yourself is why you're going the solo-route. As a solo founder myself, I'm fine with the tradeoffs because it affords me certain other liberties. Do some soul searching and get in synch with yourself.
One of the compensating measures I have is a Braintrust with other solo founders. It's a pretty good place to bounce ideas off of other people in similar situations. Let me know if you are interested in joining.