For investors who are buying cash, which denominations and what year would you recommend?

I'm looking to diversify my investments. While I do earn dollars for a living, I've never considered them as a way to store or define wealth, but I hear a lot of people are investing in cash now. So, I'm looking for answers about which ones to invest in.

Would you recommend those that went into circulation in 2020, 2021, 2022 or should I hold off and buy those from 2023 as they may be more rare. Also, do you think $1 bills, $5 bills, $20 bills, or $100 bills will appreciate in value the fastest? Or should I buy something more unique like $2 bills or $50 bills?

Edit: In case you can't tell… I hope someone got a good chuckle from this.