Found a few PCoption related threads on the forum click here.
PCSpecialist threads click here.
For good value, you'll be hard-pressed to find better than Mesh click here. After the many complaints, I can understand why it's not everyone's first choice, but remember people mainly tend to post bad experiences, & for the large quatities they sell their failure rate could be similar to many others.
Also consider Cube247 click here. Couple of their 'gaming' PCs for just under £1000 - click here & click here.
Reviews of some of their PCs: click here, click here, click here & click here.
PCA forum postings click here.
Good luck with final choice & purchase. G