Solo Ads versus PPC campaign, which one provides more responsive leads?

With good quality solo ads from providers that have done a good job developing some kind of relationship, in addition to targeting according to a known interest, you get what amounts to a respected social reference. It's like when a friend/neighbor tells you a certain contractor does good work at a fair price versus merely coming across an ad in the Yellow Pages by a contractor claiming to do good work at a fair price. They are both targeted advertising, but the respected reference helps to add authority to the marketing communications by the one company versus the other.

Of course, just like in real life with expert contractors coming to look at potential work at a person's home, some people just want to pick an expert's brain for free info to figure something out to do themselves, or they simply can't afford the services/products being offered. You will encounter these, regardless of traffic source, but they are exceptionally common through 7Search. All things being equal, a solo ad to a targeted list that hasn't been recently oversold to or neglected will produce more responsive opt-ins than PPC in general (but especially the likes of 7Search).