While I have a number of brands on my equipment, I have some brands that I have come to prefer. And, in the majority of cases, my purchase was affected by the shop I was affiliated with, and what they carried.
For example, I have a number of Halcyon wings. I 'grew up' in a shop that carried Halcyon, the owner was a particular Halcyon fan, he and I became good friends and dive buddies, and I got very good pricing. I also heard good things (OK, some cynicism as well) about Halcyon, so buying my first Halcyon wing was easy, and I have subsequently added to my inventory. Over time I realized that I also got VERY GOOD service and support from Halcyon, so I am a fan. Unfortunately, neither of the two shops I am affiliated with now are Halcyon dealers, and I also prefer to NOT pay MSRP.
So, I have also added some Apeks wings to my collection, and I very much like them. If I get a chance to get a good price on an(other) Oxycheq Mach V, I would probably buy one, simply because of the very good things I have heard about that particular model. In fact, I bought one on eBay last Fall for a diver that I had persuaded to go BP/W, and she LOVES it.
My first regulator was a Zeagle, a brand that was also carried by my first shop. I subsequently bought a number of additional Zeagle regs on eBay, I became credentialed to service them, and still dive them even though the particular reg (50D) is no longer in their product line.
When I started tech training, I got a good deal, from the same shop, on some Apeks regs (ATX200s). I found I really like them, they breath well, the first stages are heavy (so they put some weight right where I want it - high on my torso), I became credentialed to service them as well, and still dive them. The DST is a particular favorite, along with the XTX50 second stage. I am sure that other brands are very good as well - ScubaPro for example - but I feel no need to diversify, as long as my Zeagle and Apeks regs meet my needs. Although one of my current shops carries Aqualung, and therefore Apeks, they really prefer to sell Aqualung because of the margins, and I have been encouraged to consider using Aqualung regs. But, I have no interest in any reg in the Aqualung line, even though the brand has a reasonable reputation and I have access to favorable pricing.
I wear Henderson wetsuits. Every shop I have worked with has carried Henderson, so it was a natural for me to go with that brand when I bought my first suit. I really like them, and feel no need to change, although I hear good things about about brands (Bare, O'Neil, etc.). I also have found that Henderson service and support after purchase is superb.
Backplates are Dive Rites and OMS, not because of my perception of any particular superiority, rather because I picked them up on eBay at a good price, and I am happy with them.
The bottom line, which formed the basis of my poll responses: I have brands that I prefer, because of my familiarity with them as well as their reputation, because of the availability of good pricing through the shops I have been affiliated with, AND because I have been able to meet my needs with products in each of the brand lines.
There are lots of other good brands out there, I can't say that one is clearly superior to all others, or that my preferred brands are somehow uniquely better. But, they are good, and work for me. There are also some brands that I would prefer to stay away from, because of reputation as well as country of origin, and attractive pricing would not make any difference in that preference.