Juice, ultrafire, gtl?

What are the best CR123 3.6 or 3.7v batteries I could use?

It depends on what you need the battery to do. Some li-ion cells have great capacity, some can crank out the current, but you have to choose, you can't have your cake and eat it too :-(

keep in mind, also, CR123a is a primary, non-rechargable lithium cell, where-as its rechargeable li-ion equivalent is usually referred to as 16340.

Please clarify if you need high power, or if runtime is more important and high power is not needed, and I'm sure someone will chime in with suggestions.

AW makes a good 16340 and so does Efest. If you want to find out more than you ever cared to know about battery tests/comparisons, check out one of the flashlight or electronic cigarette forms. Those guys are serious about their batteries.
Welcome to the forum ! If you have trouble locating info with the search box at the top of the page, try the long search box at the bottom of the page, it works a lot better for me.
I haven't tried the others you have listed, but the GTL's I got were junk. They were not even close to the capacity stated on the battery.
There is a member named LarryDFW, he sells batteries, not sure about 16340. Might check his sale thread. He only sells quality cells far as I know.