I have a very small company / startup mindset but to me co-founder is really as impressive as titles get. I'd just focus your resume on what you did there. To me that experience counts for a ton since founders have so much less supporting them.
I strongly suspect most people here on HN have a startup mindset. HN's direct and obvious connection to YC filters for it.
When my startup failed and I was looking for a new role most hiring managers I spoke to were impressed enough with my resume but also had reservations about hiring me as they thought I'd get bored and want to do another startup within a year or two. Playing up the co-founder title might not be such a good idea. Everything else is spot on though - experience is far more important than anything else.
