In addition to the excellent services mentioned in the article, I'd like to recommend Rollbar (http://rollbar.com/) -- we've been using them for almost a year and have come to rely on them exclusively.

Their major selling points for us were GitHub integration and filtering by user-agent/other strings (baiduspider tormented us for a while), plus their packages for logging server-side errors (we use them for Node.js). Their price point is also very generous for startups :)