EV2 and ProTarget are 1-stage with a pre-spring and if you don't fully follow through there can be a tendency to hair trigger i.e. it goes off as soon as you touch the trigger (I had AA service and replace the sear but poor trigger technique can still lead to the sear not dropping fully - i.e. it is a shooter problem rather than an inherent design problem). I used to have to pull the trigger after release a couple of times to make sure the sear had dropped but it was my bad technique in the main by not pulling all the way through after the pellet flew away. The AA 400s are very nice 2-stage triggers and if you advance to 2nd stage you can release and it goes back to the 1st.
The LG300 is similar but less prone to hair-trigger and a habit of a firm cocking lever pull tends to make sure the sear is fully set.
The Anschutz 2002 trigger is brilliant once setup. I had one with a b**gered about spring which made it way too light. I bought a replacement spring and after a short struggle it was in place and it now has a definite spring tension for both 1st and 2nd stages (if the spring is deliberately weakened then you get a bad interaction between the various settings - I still have the bad spring if anyone wants a photo of what I mean). Buying a used rifle has taught me so many things to look for (in old and new mechanisms!). When out of the stock you can see if 1st and 2nd work correctly by observing that you can reverse the sears by releasing the 1st stage pressure i.e. everything goes back to where it started, if the settngs are incorrect it ends up somewhere between 1st and 2nd and is unpredictable.