Based on our record, Y Combinator Co-founder Matching seems to be more popular. It has been mentiond 1 time since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
One idea I just remembered is to find a business co-founder that already knows a market well and sees an opportunity. Startup School's co-founder matching service is quite good. Source: almost 4 years ago
MagicBus - Dynamic ride matching and booking for vanpools, shuttles, and other shared transportation
CoFoundersLab - Meet 250,000+ entrepreneurs online
Bus.com - Organize charter busses for events
Founders Nation - Find or become a startup cofounder
uberCOMMUTE - Carpooling at the press of a button
Findnlink - Find people to work with on your ideas.