There are a surprising amount of exclusives on the system right now;
Golf Story - Fun little RPG that the story and quests revolve around golf
Kamiko - Top down view action puzzle game. Cheap and easy to get into.
Mario & Rabbids - Turn Based Strategy game that is a lot like X-Com. Super cute. and fun gameplay
Splatoon 2 Third Person shooter where you aim for the ground as much as other players. There is actually a really fun single player to this, a very addictive and easy to get into online player vs player mode, and a pretty rad mode where you join 3 other players to combat rounds of AI enemies.
Super Bomberman R This game had shitty reviews when it came out, but has since been patched a bunch of times, and I enjoy it a lot. It's as fun as ever to bust out for mutliplayer, and the campaign is 2 player co-op. What's really nice is you can play 2 player with 1 switch because you only need half a joycon.
SnipperClippers Another bad ass co-op experience that you can play with 1 set of controllers
There are a lot of great multi-platform games on the system too
Puyo Puyo Tetris - This version is bad ass because it's a solid version of Puyo, and of tetris, but also includes some sweet mashup versions where you play both simultanously or both switching back and forward between the two types. Bad ass, and playable 2 player with 1 set of joycons
Wonder Boy: The Dragons Trap - Runs great on the switch, not sure why you'd want this on another platform since it looks the same and plays the same, except you can take it with you or play it off screen.
Sonic Mania - Another game that runs the same on switch as it does on the other platforms
Shovel Knight Treasure Trove - Again, runs the same on switch
Blaster Master DX - Port of 3ds game which is a new blastermaster game; looks and plays great on the switch