I bought two computers from Avaxos, I've only set one up so far. But it runs like a dream. Fantastically packaged, easy to follow instructions, simple setup.
The website process is excellent. Having the feedback before you buy, of whether your components are compatible is absolutely necessary. Especially if you're new to/overwhelmed by the myriad computer parts.
Delivery was as estimated on the site, feedback on the build was accurate and useful.