The best currency for investment depends on several factors, including your investment goals, the level of risk you can tolerate, and the current economic context. Here are some popular currencies to invest in:

Cryptocurrencies:

1. *Bitcoin (BTC):* Bitcoin is considered one of the most popular and stable cryptocurrencies and is regarded as a long-term investment option.

2. *Ethereum (ETH):* Ethereum is one of the well-known cryptocurrencies and is used in many financial and decentralized applications.

3. *Altcoins:* There are many altcoins with unique technologies and specific uses, such as Litecoin (LTC) and Cardano (ADA).

Stablecoins:

1. *Tether (USDT):* Tether is considered a stablecoin that is pegged to the US dollar and is used as a means of hedging against volatility in the cryptocurrency market.

2. *USDC:* USDC is considered a stablecoin that is pegged to the US dollar and is used in many financial applications.

Investment Tips:

1. *Research:* Research the currencies you want to invest in and understand their technologies and uses.

2. *Diversification:* Diversify your investment portfolio across different currencies to reduce risks.

3. *Cautious Investment:* Invest cautiously and do not invest more than you can afford to lose.