Personally I think the FAA system is better. Minimal fuss (not their fault the UK CAA is so OTT) to acknowledge that you are competent to fly and 'validate' your licence, but a bit of diligence to make sure you are familiar with the rules of US Airspace.
It is a bit slack that I could have jumped into a G-Reg plane and flown around the UK with not 1 second of advice/training on - the fact flight following doesn't exist, IFR without a clearance is perfectly normal, you really can't over fly a TMA, the airways really are Class A at 3500 ft, PPR as a concept exists, you don't close your flightplan, and buying fuel doesn't get you free landings!