I'm also using both vendors with a couple VPSes at each. I've had one outage with Slicehost when they needed to replace a drive in one of my servers. I wasn't

I'm also using both vendors with a couple VPSes at each. I've had one outage with Slicehost when they needed to replace a drive in one of my servers. I wasn't even aware that there was a problem prior which shows how proactive they were. The outage was short and on schedule and everything came back up, as expected. I've had excellent experiences with tech support in both organizations. Both are very responsive. Both have pretty strong user communities with Slicehost having a bit of an edge on documentation, if you aren't already comfortable with your own admin. Both have active IRC channels. Honestly, for me they're almost a coin flip. When I get ready to acquire a new VPS I see what each is offering at the time and go with the biggest bang for my buck. The article is helpful, even if unscientific, at determining the efficiency of the bang.