I have a variety of triggers including mil-spec, Geissele, JP, RRA, and Larue. In terms of value, I don't think the Larue MBT-2S can be beat for a 2-stage trigger. My Larue is the equal of my Geissele G2S and is significantly better than my RRA varmint 2-stage. FWIW, all of mine are curved.
Larue also has single stage triggers, but I haven't tried them. Reviews are somewhat mixed on them. I like my single stage JP's, but they came in the rifles I have them in, so I'm not sure what model they are or how much they cost. IIRC, they're pretty spendy. In general, I prefer 2-stage in AR's, but the JP's are good enough that I'm not going to swap them.