The four best altcoins to consider buying now for potential explosive returns are ¹:

- *BlockDAG (BDAG)*: This altcoin has raised over $269 million in its presale and has confirmed listings on 20 centralized exchanges. Its hybrid system combining DAG and Proof-of-Work technology offers fast speeds, low fees, and a secure network. With a current price of $0.0020 and a predicted listing price of $0.05, BlockDAG could see a 2,400% upside.

- *Stellar (XLM)*: Stellar is a leader in cross-border payments, offering low-cost and high-speed transactions. Its token, XLM, powers the network and facilitates smooth transactions across borders. While its price hasn't made any big moves lately, Stellar continues to be used for global money transfers and remittances, making it a solid choice for those looking for stability.

- *Aptos (APT)*: Aptos stands out with its unique consensus model and Layer 1 focus, giving it a different place in the market. Although its price has slid recently, Aptos shows strong developer activity and growing interest in its Move-based smart contract setup. If new updates or capital inflows arrive soon, Aptos could reverse quickly.

- *Chainlink (LINK)*: Chainlink remains vital to DeFi thanks to its data feed and automation roles in smart contracts. It's expanding to new networks and projects, keeping it in play as a top altcoin to buy for long-term holds. While it may not explode in the short run, its ongoing utility makes it a key player in the ecosystem.