The listed requirements are general enough for me to list a laundry sheet of recommendations, so I would consider narrowing down exactly what you are looking for.
Reliability: I expect the gun to run well in __moderate_____ conditions, using __handloaded______ ammunition, on _____300_____ rounds shoot schedule per___weekend_____ (time period).
Accuracy: I expect it to group ___1____MOA for _5__ rounds average shot group at ___150____yards/meters, using____handloaded________ammunition.
Magazines: I would like to be able to equip it with ______relatively available_______magazines, or I don't care, I'll buy uber expensive and limited mags for peculiar systems, no biggie.
Ammunition: I would like it to be readily available at local sporting goods stores in my particular region (yours isn't stated), or I don't care, I'll order unique calibers online in bulk, then hand load for it.
Terminal ballistics: I need it to penetrate or perforate _____<whitetail_______ mediums, with _______deadly______results at <200 yards
Recoil: I do/don't care about recoil impulse, and my kids or small family members might like to try this some time as well.
I would like to enjoy shooting this all day from time to time.
Furniture: I'm a monster of a man, exceeding 7ft, 300lbs, or I'm 5ft 2" with a small stature, I need appropriate furniture to fit the gun to these anatomical considerations.
6' flat by 175, fit.
Trigger: I would like _~3_____ trigger weight and 2-stage or single stage operation are fine.
These questions, with examples can help you narrow down exactly what you're looking for.
