Here's a list of popular altcoins that could potentially perform well during the next alt season:

DeFi Altcoins
1. Uniswap (UNI)
2. SushiSwap (SUSHI)
3. Curve DAO Token (CRV)
4. Aave (AAVE)
5. Compound (COMP)

Gaming Altcoins
1. The Sandbox (SAND)
2. Decentraland (MANA)
3. Axie Infinity (AXS)
4. Enjin Coin (ENJ)
5. Gala (GALA)

Layer 1 Altcoins
1. Cosmos (ATOM)
2. Solana (SOL)
3. Cardano (ADA)
4. Polkadot (DOT)
5. Near Protocol (NEAR)

Metaverse Altcoins
1. VR First (VRF)
2. Star Atlas (ATLAS)
3. Illuvium (ILV)
4. My Neighbor Alice (ALICE)
5. UFO Gaming (UFO)

Other Notable Altcoins
1. Chainlink (LINK)
2. Polygon (MATIC)
3. Stellar (XLM)
4. Tron (TRX)
5. Hedera Hashgraph (HBAR)

Please note that:

1. This is not investment advice.
2. Alt season performance is highly unpredictable.
3. Always do your own research (DYOR).
4. Never invest more than you can afford to lose.

Stay safe, and happy investing!