In my "best of" list I mentioned a few biners that I think are stand outs.
It has been a while but I haven't counted how many different styles and brands of carabiners I currently have. It is more than six.. What I actually use is three or four styles and generally just two, maybe three on a regular basis.
I generally try to hold on to my gear so I have carabiners that go back a few years. If you think super light and small 'biners are a "new deal" check some of these out.
The blue Latok mini biner is rated at kN 1700 and weighs 28g. The newest green Metolius mini is rated at kN 2200 @ 26g.
I have to agree with Colin Haley, who once described the Metolius by saying "they finally made a biner that is too small". I have them. I don't use either.
A biner I have used a lot is a bent gate. One of the first imported into the US, the blue gate "New Alp" imported by Climb High from France in the late '70s is on the left. Rated at kN 220 @ 56g. I did most of my hard rock climbing with that biner on my rack. The idea was a quick clip and it worked very well for that purpose. In the middle is a more recent bent gate by Black Diamond that I still use in some situations 19 kN @ 46g. And on the right my current favorite the Trango Super Fly 30g and 24kN
The runner up for my own use on the Trango is the BD Oz @ 30g as well and 20kN. Pretty much the same size and feel. BD is off on the numbers a bit but I use both on my rack now depending on the price they can be had at.
I use three locking biners depending on the required use. Left to right, Trango 40g @ 24 kN, Black Diamond Gridlock 78g @ 22kN and the Mammut 78g and 24kN.
And I have a few I am still undecided on. Trango on the left, a small Camp @ 22g and 20kN and the new Petzl @ 30g and 20kN
And finally a carabiner that impressed me while we watched it being destroyed at the Grivel factory.
The hard anodized Grivel Yamma K2W biner, 34g and 27kN that is individually tested and serial numbered in production. An extra 3 to 7 kN bmp in stregth is a big bump in all these lwt biners. No quessing either as Grivel tests biners like this one to failure on a regular basis.
If nothing else I like consistency. I find it annoying to climb with all sorts of differing sizes and styles of carabiners on my rack. So I try not to, even if that means we use my rack a lot :-)