chrisJ, 2600+ days in mouz (2013-2020)
JW if you combine his time before Godsent and now
ChrisJ in Mouse JW in Fnatic and Flamie in Na'Vi
Does rain count? Kinguin roster was bought by G2 and G2 roster was bought by FaZe
Xyp9x, dupreeh and device could be argued since they've been the same core team since 2013, they've only been under Astralis since 2016 though which is lower than EliGE and flamie.
all time - chrisj
rn - flamie