The going wisdom seems to be that the EU's Galileo is the most accurate system for civilian use. GPS has undergone frequent systematic update for almost a half century.
Indeed. i have some GPS receiver modules and had wondered about this data, I had assumed it was imprecision in my device or something to do with a satellite moving around. I'll have to plug it in and go back for another look.
Two things amaze me about GPS. First, that there are still four Block IIR and seven Block IIR-M satellites operational; these had 7.5 year design lives and were launched by 2004 and 2009 respectively. Second, that L1C, L5 and L2C are all still pre-operational thanks to the OCX debacle. L1C and L2C really modernize the signal structure to improve accuracy.
What's interesting to me is how out of date US GPS system is compared to China's BeiDou
and while most US GPS receivers will use Russia's GLONOSS, China's BeiDou is blocked
https://news.ycombinator.com/item?id=47849174