Speaking with limited experience here but I just finished my first AR and I used a Geissele SSA-E in it. Let me tell you what though, it's one of the nicest triggers I've ever got behind. Suuuuuper crisp and smooth. Realize they are around $240, but you can find them cheaper sometimes. I bought mine for $180 from PSA on sale. To me it was money well spent. YMMV.
