I don't know that either one is 'better', more like different.
Some pro's & cons I've noticed..
The CPR box...has a smaller profile inside of the tank which saves space. It requires the use of an Aqualift pump to keep air out of the weir so that you don't lose siphon. I have read that people have a difficult time installing these and issues with bubbles in the tank (there is a forum about all this on their website)
The Lifereef box uses a tube, which some folks frown upon due to the challenge of starting the siphon (piece of cake if you mod the UTube) I have a very similar OFB on my 33g cube tank and have never had an issue with it. Lifereef claims it's boxes don't need to be restarted manually after a power outage, I have no info on that, but they sure sounds interesting!
Hopefully someone here who uses one will chime in.
A couple of pic of the mod..uses a small piece of rigid air line, a foot or 2 of regular airline and one of the pictured do-hickey valves that open & close.
I have been using a lifereef overflow for the past 2.5 years on my tank and it has never lost siphon or failed to restart after shutting off my pumps. As to having to mod the U tube, its not necessary. I just snake up an airline into the tube, connect it to a venturi outlet on a maxipump and it removes the air for the siphon to start. Afterwards just pull out the airline. Quite easily done