I have several PSA's, and am pleased with them. I have several rifles in different configurations for different applications. The form and features you need are really driven by what you want to do/how you like to shoot
When target shooting, do you like shooting stuff like gongs/cans, or do you really like shooting tiny groups? Do you like "run-and-gun" fast shooting?
Do you want to use your rifle for varminting or HD?
For myself, I came ftom bolt guns and like precision. Most of my rifles are stainless 18" w. Wylde chambers. I get better accuracy, but give up some portability with the extra barrel length. When I'm scouting, hiking, or coyote hunting, I use a 16" setup. The accuracy is still decent, the rifle is set up for fast target acquisition. Its still accurate enough to be fun plinking. My 20" is most accurate, but never gets carried in the field. The extra weight doesnt justify the performance gains unless Im groundhog hunting.
If I had just 1 rifle, it'd probably be a 16". 1:8 twist gives a little longer barrel life. To be honest, I doubt I'll ever shoot a barrel out. The majority of guys wont either. 1:7 is fine.
Wylde chambers are closer to 5.56 than .223. Either one is fine. For 16" 5.56 chamber is more common. For my 18", I prefer Wylde. If you're not shooting match ammo, you probably wont see a difference.
Save $100 in your rifle budget for a RRA 2-stage varmint trigger.