I'm a HUGE fan of the A-bolt/X-bolt! The main differences are the X-bolt has a removable polymer magazine whereas the A-bolt has a concealed removable steel magazine. The X-bolt has 4 screws to retain each of the scope mounts instead of 2. The X-bolt has a bolt release button to work the bolt without taking it off safety.
The A/X bolts have many great features such as 3 locking lugs, 60 degree bolt lift, well designed magazine, tang safety, They come factory glass bedded & free floated barrel, fit & finish is superb for a standard factory rifle, accuracy is great, and the crisp factory trigger is user adjustable. I could keep going but you get the idea.