This upgrade should not only be determined by your monitor and plans for your kept or possible new upcoming graphics card. In order to answer this question correctly and make an informed decision i'll need a complete list of your hardware system specifications. This will help me get a "birds eye view" as to what hardware you have and future possible upgrade capabilities of the platform.Well I have 2 choices either to buy a card or a monitor cuz I can afford both now.
Lets say I want to buy first a decent 2560x1440 144Hz monitor.
And I am playing few months older games at 2560x1080 with average fps of 50 on high/ultra
Buying a new monitor and playing with same old R9 390 how much fps would I loose if I switch it to 2560x1440 instead of current 2560x1080?
Games I play are Far Cry 5,Batman Arkham Knight,Dishonored 2,Dyling LIght,Far Cry Primal,Rise of the Tomb Raider,The Witcher 3,Rage 2...I downloaded newer titles as well,but waiting to finish these games.
I mean that is not much of a higher resolution,right except this 1080-->1440p.
Buying a card would ofc mean to enable V-sync.