Sometimes it’s not about self-defense and fighting
Sometimes it all about having fun and taking friends and family to the range and showing off your toys. The AR15 is hands down the number one centerfire rifle that I teach family members to shoot on because the ergonomics and recoil are easy for even an older child to shoot. Stock adjustability makes the gun an easy fit for the young and old, short and tall. Sure there are plenty of customizations you can do but if you have an AR15, you already know this. Some of the AR15s absolutely are better than others and sometimes in different ways.
I have several Bushmaster firearms that I still have fun shooting with but they stay home if I am doing serious training. I have often looked at picking up some of the Spikes Tactical Uppers if I need to replace the Bushmasters just because the reputation of Spikes Tactical guns is so good. The real reason people like the Spikes Tactical stuff is because the company seems to have their stuff in order and even their lower parts kits are a great thing to pick up. The Mid Length and MOE uppers seem to be the most popular versions right now.