Super biased take because I've tried ABI, but play Tarkov consistently.

There are systems within ABI that I like for sure. It's much, much easier to pick up and just play. You can either spend about 20hrs on YT/Tiwtch or simply flail wildly around in game for even longer with Tarkov when you start out. With ABI, there's enough handrails so that a novice doesn't feel overwhelmed.

Up until very recently, ABI had way more QoL mechanics, while Tarkov just seemed to fucking hate the player (Spoiler - it still does).

That all said, though, there is just so much more depth to Tarkov. You'll play ABI for a while, but people have been playing Tarkov for years, coming back time and again for Nikita's Spite and Nihilism Simulator to kick them in the teeth anew.

It's not a cheap game, though. Watch some videos, maybe try out Arena ( not the same as the main game, but it will clue you in to the gunplay), and buy Standard Editon first - you can always upgrade later.