[softwarejim]

The assumption that your choice is a binary one is silly. Its never either/or. Its always both.

The first product you build are in a client driven business structure where they are telling you what and how to build it. Then if you do that well enough, you can transform yourself into a product business.

[stevejalim]

I agree, the best of both worlds is still an option.

Get to a level when you can afford to not be working for a client all the time, and then plan your time to spend, say, a fortnight a month doing client work, then the subsequent fortnight working on your own flux capacitor.

That way, you might even avoid needing to source funding, too.