Polygon has been one cryptocurrency that has been on the trend list this year, and so far I believe that it would be a good coin that would maintain a good level of growth as time goes on. As for Stellar, I was investing in it earlier when it was came out, because it looked promising and I also got the airdrops they did when they released earlier, but as time goes on it started to depreciate heavily and seemed like it wasn’t going to make its way back up again, so I had to give up on it.
Well, later I came to understand that it is how it’s going to be, because new projects tends to start with high price and when the projects finally launches, they lose value because a lot of people rushes to sell their coins. But right now I seethe possibility for this coin to still get back up, and that will likely happen in the future.
Polygon is a really good project with potential to take the "De-Fi" world by storm. It's cheaper than ETH and even Binance Smart Chain. I've used it a couple of days ago, and the experience was amazing. Transactions cost less than a cent (USD) while confirmation times are near-instantaneous. I think it's a very underrated coin, considering all of the benefits it provides.
There are other altcoins which have the potential for growth such as Cardano, Avalanche, and Polkadot. These are rock-solid smart contract platforms with the ability to compete directly against Ethereum. Nowadays it's all about "De-Fi" and NFTs, so most coins with smart contract functionalities are sure to increase in price like crazy. As long as you play your cards right, you'll have nothing to worry about. Just my opinion