Thanks for the Pause Game tip.
Auto reconnect is a must for any serious client.
The MTA server list is ancient and ugly, it is also live, accurately sortable, lists players on servers, and displays dozens of servers in one frame rather than just a few. Perhaps a discord like large view/tiny view switch would augment FiveM.
But you are right nothing matters, not sync, not features; beyond server client stability. GTA 5 client is one week stable. MTA client is one month stable. FiveM client crashed 5 times in 1 hour this morning. Not even close. MTA server is forever stable. But my FiveM Server still requires daily rebooting due to CURL fails.
That is what FiveM really needs in my eyes. Ruthless and constant debugging.