As the title says I was building a new rifle and I'm wandering which one to go with.. I was wanting to know how they compare as far as felt recoil if both systems have lightweight bcgs and buffers.... and which would be more reliable?

Both will be equally reliable. The piston gun will stay cleaner and cooler as you shoot. I use an AA piston gun with XLP gas block, low mass carrier, and a JP silent captured spring with the lightest spring. Amount of felt recoil is no different than a DI gun. Recoil impulse is a little different, more of a straight back impulse. Either will do well for you. I love my piston gun though. Coupled with my SJC Titan comp, the gun doesn't really move when I shoot.