Obliviously GTA 5 has always been the King for Online Multiplayer Games Since the Game Was released...But these are some other games which are more Addictive and fun to play with Friends and random Stranger

1. Fortnite

Fortnite has been the Trend for 2017-18 , the game was released on 25 July 2017 and has been nominated for many game Awards... One of the best Online Multiplayer Game...
And also YOU CAN PLAY WITH
Crossplatform Supported
play with PC and Xbox and Ps4 Users
THE GAME IS FREE

2. Dead By Daylight

Dead by Daylight is an asymmetric survival horror online multiplayer , Released on 14 June 2016, and trust me this game is soo addictive and gives you the chill all the time + with friends more fun++

3 Call of Duty Franchise

Nothing to say about this.. We all know call of duty is more fun with Friends as it is a shooting game.. New games every Year by COD

4 PUBG

PUBG is the beating heart of multiplayer gaming in 2018, following a near-mythical rise through Steam during its Early Access phase last year

PUBG is now on ANDRIOD AND IOS

5. Rocket League

Car FootBall Game best with Controller and also can play crossplatform with other player, awesome Fun and addictive

THEIR ARE SOO MANY OTHER ONLINE GAMES But the above are more fun than that

CSGO
Overwatch
FiFa
Borderlands: The Pre-Sequel
MineCraft
Battlefield
star wars
Team Fortress
Need For Speed
ARK
GARRY MOD