In my experience, the trigger in a LPK is a crapshoot. Sometimes they're OK, other times they're pretty lousy. I've built with Stag and DPMS kits and have had no problem with either. Arfcom users haven't had major problems with LPKs from Spike's, Palmetto, Stag, or RRA. The big gripe with DPMS is that some of their roll pins are very tight to install.
Tools and knowledge make the biggest difference. If you don't know what you're doing or don't have the right tools, your LPK install will be a big PITA and may result in scratched or broken parts (support those trigger guard ears!!).
If you want a very nice trigger, check out the offerings from Geissele. I have their SSA (Super Semi Auto) model and it's everything I want in a carbine trigger. The SSA is their semi-auto version of the SSF trigger (Super Select Fire). The SSF is currently in service with some military units, according to Geissele.
If the price tag of the SSA scares you (around $170, street), Geissele just came out with the S2S (Super 2 Stage) that is priced around $125.