Canjar is gone, but sometimes the single set version for the no.1 shows up second hand, gunshows, or interent sites. It has a trigger shoe with a little tab that goes forward during the setting of the trigger. Can be used as a conventional or set trigger.
Kleppinger is an Austrian single set type trigger that is available from Brownells, and other spots. The appearance is different from the oem trigger. Fairly pricey, but nice.
In some set triggers one has to get used to trigger movement after release.
The Moyers is kinda a replacement type of conventional trigger that minics the old original 3 screw Ruger No.1 trigger(has sear engagement screw). Appearance is similar but not same as the oem Ruger two screw or three screw trigger system. About 50 bucks per. Some like them, some don't.
Some people use the oem 2 screw trigger as is for appearance sake; however some gunsmith's drill the hammer for a stud near the sear surface engagment, to space off the hammer/sear fit ie for a lighter trigger pull. The hammer is hard and needs carbide tooling for the hole, ..........as in most things, lots of care(common sense) is needed for how much to offset. I prefer that to some gunsmiths grinding of the engagement on the hammer. The oem hammer is a factory fit part only.
Finally there are some gunsmiths that make their own version of trigger for the No.1, most are in short supply and usually fairly $.
Finally, I have seen a trigger shoe do some good for some triggers, at least in the psyche. Larger surface area gives the feel of a lighter pull.
I bet that 22lr No.1 is fun to shoot; not many do that type of thing.
The "best" readily available trigger is the Kepplinger. Right now they run about $250.
I actually prefer the Cajar but as they are no longer made one has to find one somewhere. Ther do appear from time to time on Gunbroker and Auction Arms. I've managed to score 3 in the last few years in the $125 - $150 price range.
I have them one my #1s in .17 Remington, 22PPC, 22BR, 222 and 22-250AI. It was just easier to for me to get the feal of them. THe shoe can be set as low as 2 oz. and the trigger as low as 2 pounds.
You also run across the original 3 screw triggers from time to time when guys replace them, usually with the Kepplinger and then sell them on the net. I've bought two on the last couple of years and replaced the 2 screws on a couple of my newer #1s. Luckily the vast majority of mine are "Old" and have 3 screw triggers.
Right now if I had to have a trigger and didn't want to wait I'd buy the Kepplinger.
I have had a Griffin and Howe Number One trigger in my parts box for at least 15 years. It is what they use (used?) when customizing a Number One, essentially a new steel blade to replace the existing trigger.
I would have to take a look at it to see how many "screws" it is made for, but it is really an unfinished piece of steel that still needs to be worked down to its final dimensions. Sort of a rough blank if you will.
I'm pretty sure I bought it from them after seeing one on a bespoke built rifle at the Custom Gunmaker & Engraver's Guild shows (I used to go pretty regularly) but decided to use a Kepplinger instead. Perhaps I will use it someday on another Number One project.
I have never used a Kepplinger trigger, but have heard a great deal of praise for them from those that have. I have used the Canjar and the Moyer. The Canjar triggers are great, but no longer in production and are somewhat difficult to locate.
I have had good luck with the Moyer triggers but have seen postings from others that did not care for them. They are a bit wider than the factory trigger and I like to contour them a bit, polish the edges so that they are pleasingly rounded and smooth. They are available in stainless or blue and are cast steel instead of cast aluminum like the factory trigger.