Best Free Multiplayer:

Grapple Tournament - arcade shooter with complete 3D movement - running, double jumping, wall jumping, climbing and using your grappling hook to swing around like spiderman. 

Rec Room - tons of mini games, Co-op quests and escape rooms are the best game modes.  Private games are better as this is overrun with kids.  

Horizon Worlds - Meta's own world, similar to re-room, lots of great escape rooms

Bigscreen - Watch video and movies with friends in virtual theater environments

TraVRsal: Amazing use of tricking your mind into thinking you have a much bigger playspace, no artificial locomotion - 1 to 1 walking

Grab - Parkour game with climbing, jumping, sliding and swinging

VRChat - Social environment that has some of the weirdest stuff you'll find online

Best Paid Multiplayer (we play these regularly):

Walkabout Mini Golf: $15 - Buy this 1st  - Fun, relaxing, good for kids and adults - up to 8 players

Racket Club - Similar to pickleball but designed for a smaller play area, can play singles,doubles or against bots.  Requires at least 6.5x6.5ft of play space.  

Breachers: $30 - 5v5 Team based assault game

Dungeons of Eternity: $30 - 3 player co-op dungeon crawler

Mannequin: $20 - Prop-hunt style 2v3 social stealth game

Bocce Time! : $9: Great casual game, ideal for 2v2.

Tower Tag: $15 User your body to dodge bullets around towers - no motion sickness

Demeo Battles: DnD PvP (1-4 players)

Also Great Multiplayer:

After the Fall: $40 - 4-Player co-op zombie shooter, really fun

Demeo: $30 - DnD themed table-top game

Loco Dojo Unleashed: $20 - Mario Party in VR, lots of mini games for up to 4 players

Tetris Effect: Connected: $30 - Super trippy version of tetris with music that syncs to the the blocks, lots of multiplayer options

Cook Out: $20 - Co-op cooking game

Room of Realities - $15 - Great co-op escape room with 9 levels

Contractors: $20 - Military FPS - pvp and co-op modes

Catan VR : $15 - The Classic board game in VR, supports 4 players multiplayer

Among Us: $10 - 4-10 player social deduction game.

Best 2 Player Games:

Racket: NX: $20 / Free Demo -  3D competitive 1v1 and co-op racquetball with power-ups

Crisis VRigade 2 - $20 - Time Crisis/ old school light gun arcade type game - no artificial motion, great 2 player co-op mode

Puzzling Places: $15 - Jigsaw puzzles in 3D

Blaston: Free -1v1 slow-mo shooter

Windlands 2: $24.99 - Fly through the air, single player and 2 player co-op options

Glassbreakers: Champions of Moss: Free1v1 Tabletop action game

Space Pirate Trainer - $25 - This has an 1000sq ft Arena mode - like playing real physical lasertag

Carly and the Reaperman: $20 - Asynchronous multiplayer - your friend plays on PC and you play in VR together

Ultimtechs: Like Rocket League in VR - 1v1 or 2v2 matches