Bitcoin.
Easy to buy, harder to mine.
As a newbie you are, to mine Bitcoin it depends on two things.
1. Your electricity must be very cheap.
2. Your pocket must be heavy.
It costs a lot to mine Bitcoin in 2025 and its only getting started, mining isn't for many people anymore, there are also some things that can happen after you get everything running.
A hardware part can die on you, how long your equipment will last will always remain a misery.
I will choose to buy and hold or else I really want to mine as a hobbist, the past you was a miner? If no I recommend you think this through very carefully.
Well I do not think anyone can go big and make good money anymore.
You can go small and if you need a space heater it is okay to do.
Avalon Mini 3
https://www.ebay.com/sch/i.html?_nkw=avalon+mini+3&_sacat=0&_from=R40&_udlo=800&_udhi=1%2C500&rt=nc&LH_PrefLoc=1Now you will not get rich on it.
My units you will not get rich on them.
or real small
https://altairtech.io/product/bitaxe/but to think you can buy a container and fill it with 100 miners and play with the big boys nope I would advise against it.