Here's something to consider: whatever your first game ends up being, you'll probably love it because it's your first game. Years ago when I decided I was ready to buy a game, I saved up and went to a pinball show and basically bought the cheapest DMD available. It was a World Cup Soccer '94 that needed a little work but was a good price. I don't like soccer. I had never played the game before. But I saw ramps and it looked cool so it was either go home empty handed or give it a shot.
Once I got some help fixing it up, my friends and I played it constantly. We loved it and played it a lot because we had a pinball machine in the house and that alone was cool enough. While it has been a long time since I owned one, I still think WCS94 is a fantastic game. It's objectively a good game, but there's a layer of "first game" charm and nostalgia too. And I have definitely heard other people have a lot of affection for a really random first game that was whatever they could afford (unless it turned out to be a bad buy/maintenance nightmare).
For your sanity, i'll refrain from saying what I paid for that WCS94 back in 2007.