Gatling is my preference.
It's the successor to JMeter, self-hosted on a server (or multiple servers), and provides a lot of useful features. Some very nice reporting, full useragent control, path of access if you want (visit /index then /post then POST a comment then reload /index then...), and lots of other stuff.
It's a bit of a pain to learn to script, but it's also much cheaper if you're testing frequently than the various SAAS solutions.