Paying for tools is a smart choice. If programs like Keynote and Mail.app were actually profit centers for Apple, I would imagine that we'd have far better support, fewer long-term bugs and and most of all, a vibrant, ongoing effort to make them better.

— Five Thoughts on Software by Seth Godin

I completely agree with this, after seeing Google eventually take down Reader, I've always swayed towards paying for tools and services when I can. They're more likely to be still running in the long term, offer greater support and they are updated more frequently to ensure their customers are still getting value.

There are exceptions to this though, but this is a rare exception only made possible by exceptional companies.