I've found the latter to be considerably more lucrative and engaging. The work I've done ranges from language teaching software to automated trading bots for second hand books.
The market for this sort of work is so screamingly hot right now that if I did all the work that my current clients are asking for in series, I'd be booked into early 2015. And that at a daily rate that the me of three years ago would have trouble even asking for at the negotiation table.