Just got an xtx myself, with initially the same issues, i enabled under the 'Gaming' tab in the Adrenaline dashboard , 'Anti-lag', few options down, set 'Wait for virtual refresh' (Off, unless aplication specifies) then below under Advanced tab 'Frame rate target control' and set it to 140, just below the 144hz of the monitor, so it doesnt overshoot.
At the 'Display' tab, next to 'Gaming', 'Adaptive Sync Compatible' on, asuming you have a VRR compatible display, if not, use 'Radeon Enhanced Sync' under the previous mentioned 'Gaming' tab.
Set the framrate in the GW2 settings itself to unlimited, disable v-sync.
I use Windowed Fullscreen, in the settings, don't know if that matters.