Daniel defense vs rock river lowers
Yes I'm not planning on getting a good aftermarket trigger for a little while I can use that money to complete the build quicker and yes only a little xp with them but when I'm done and ready for trigger upgrade I'll definitely look into the geissele but right now I'll only be able to possibly complete the lower within the next month the upper will be a while.
Daniel defense vs rock river lowers
Then the DD is a great pic! As far as the lower receiver get the one on sale with a cool roll mark you like. This is your first build so have fun with it, trust me you'll be hooked and build more. Spikes are cool lowers and if you can find one UCWRG but people want too much for them.
Edit: forget the UCWRG lower, it'll never happen, but it would be cool.