If you're looking to expand your library, get the PS5. Xbox Series doesn't have any games that are current gen exclusives yet so you still have access to the entire library with your current hardware. You just don't have the graphic upgrades. I think xbox is getting its 1st current gen exclusive this month but it doesn't look like anything special and its also on Playstation 5.

The PS Plus Premium subscription actually has more games than Game Pass and it's a lot cheaper. However, it doesn't have the day one games and the PS3 library can only be streamed. It does come with almost all of the Sony exclusives you missed out on with the exception of the new releases from this year so you can get caught up.

I recommend researching release dates for upcoming xbox console exclusive games that you are interested in. If you find some, try to budget so that you can afford a Series S or X. There's not many but some will be shaking loose 2023, I think.

Or you can play the long game if you don't see anything that's a "must have" and save up for a PC since it gives you access to the Xbox games, PC games and also mods.

I use Xbox Game Pass on PC and PS Plus Premium on PS5. I haven't needed to fire up my Xbox for any reason.