Just as the title states, when the stock Messaging app wasn't cutting it, I installed Handcent. But it started flaking out on me, so I dumped it and went to the more-reliable chompSMS. I liked it a lot. But to be completely honest, I missed some of the features of Handcent. But reliability is Job 1, so I kept chompSMS for a few weeks.
<fast forward>
Then I heard that Handcent received a major update a few days ago, so I replaced chompSMS with Handcent. So far so good. I got all the features back, and I haven't had one single issue in days of texting. So if you're like me and you left Handcent for chompSMS, you may want to give the new version a spin.