I own both brands; doubles and singles rigs.
I think highly of both DSS and Halcyon, and have been very happy with them.
There are differences in price, and some varying design features. You are probably already quite familiar with the design differences if you've spent time reading up on both.....in my opinion, there is no difference in quality.
I will say that it is very hard to beat a DSS LCD 30 wit SS plate for an all around single tank rig. The shape of the wing is very streamlined, just a perfect shape for an aluminum 80 tank.
A few of my dive buddies have the Halcyon Traveler. It is a good BC, the best feature about it is the weight pockets on the back plate. Even if you are not using it for travel, it is nice to be able to make it an 8-12 lb. back plate.
The traveler come with a "cinch", harness adjustment, which is nice if you are interested in that sort of feature. At a price of $600, the traveler is a good deal.
Back to the DSS.......it's only $465, which is a steal, considering the quality. DSS also has a harness adjustment that can be added to the plate and still be under $500.
You'll see rigs that are cheaper than DSS, and some that cost more....but you won't find one that is better built.
Halcyon is very nice, I like mine a lot....but they are not better. Branding is part of why Halcyon costs more than the others.
As I said...it's really tough to beat the DSS LCD30. I like the LCD30 over the Torus26, because of the shape....but that's just personal preference.
A former dive buddy used to have the Torus26.
Have fun shopping. ;-)