I can kind of understand the swing toward Dahua - I used to be decidedly anti-standalone-DVR, greatly preferring PC-based systems for a number of reasons, but the largest one probably being just the really short feature sets and horrid menus, OSDs and controls that plagued pretty much every standalone I'd ever used (read: had foisted upon me to support). I mean, let's face it, your average standalone has traditionally been a major pain in the arse to use, amirite??
That all changed when I was given a small Dahua DVR to evaluate by another long-time forum member who originally joined up looking for help in selling a bunch of surplus equipment he'd come into, and eventually moved into reselling new gear - mostly Dahua-made - under his own label. I was very impressed with the features, flexibility, and power of the unit vs. the price point, and was quite pleasantly surprised by the intelligent layout and friendliness of the menus. I introduced the unit to my own boss... and we're now carrying the brand as a low-cost alternative to the usual Vigil systems we work with. Yeah, it's that good. Not an outright replacement for a Vigil in most cases, but definitely a viable option when a customer doesn't want to drop $3000+ on a fully-loaded system.
Said reseller had always been active in the forum, giving out plenty of free support and advice, even to people who weren't buying from him. For some strange reason, a lot of those ended up subsequently buying from him. And then recommending him and his site. Eventually he even placed paid advertising on the site.
And then, proving yet again that no good deed goes unpunished, the admin decided that all these recommendations MUST mean that people were shilling for him (it didn't help that some of his other advertisers - who did nothing more than pay for banner ads; no participation in the actual forums - were starting to complain about the way everyone else was recommending this one other advertiser over them), and aforementioned reseller and several other normally-very-active users (myself included) were banned from the site.
So most of what's left now are DIYers who still like the Dahua but aren't allowed to mention the one particular brand (if you type in his brand name, the system will auto-replace the text with "Dahua"), and the Avigilon gang who would never recommend a Dahua in any form anyway.
And yeah, those Avigilon fanboiz get pretty tiresome, like Duncan says - at least if I recommend someone look at a Vigil, I'll try to list and describe specific features that will apply to them... the usual Avigilon sales pitch seems to be, "Just try it, you never go back, I promise!" Any discussion about Avigilon support of other camera brands inevitably turns into, "Just use Avigilon cameras, then you have no problems."