Worst one by far was some guy running a reseller deal from his apartment (though I was unaware that it was such a small biz when I signed up). Overpriced, underserviced, and eventually my server kept going out for hours at a time; the guy running it claimed it was up, but I suspect he was turning the server off periodically to get me to find a new host lol. Most of his accounts were mainstream businesses paying $300+/month for small websites with little traffic, I don't think he realized what he was getting into with tgp traffic on the server.
Next bad one was mojohost, they've got a good rep but they really screwed the pooch on my account. They did try to make it right eventually but they were too expensive for my needs with tgp traffic and the service was kinda lame (I think at the time they only had one overworked tech working for them) and the server they set my account up on was some ancient PII or something. My sites kept crashing periodically, and this was at the same time I was just starting to get decent tgp traffic and was requesting partner accounts from tgps etc - it was a near constant worry. All of which I could have forgiven if not for the owner telling me they set my stuff up on something he called a 'legacy system' (i.e. outdated piece of shit that crashed all the time), tried charging me more per MBit of bandwidth the more I used (most businesses give volume discounts, not charge more per unit as the needs grow), and then after he told me it was going to cost more per unit of bandwidth from his company as my requirements grew he accused his competitors of "bait and switch" LOL.
After that I switched to servermatrix with accunet for additional server management and have been very pleased with their service. I don't think anyone else I've encountered can match their prices and support. At 20Mbit unmetered + redundant server management for $300/month, it's a bargain, but it's not for newbies. For someone looking for a more thorough management solution
www.chilihost.com seems good also, I've chatted with the owner a few times and he was very helpful and knowledgeable.