Personally I invest directly in Tron's native token TRX. We use it to run all transactions on Tron chain that is the 5th in popularity among Blockchains.
Also I have BTC on my Tronlink. As I know, it is not real Bitcoin, it is also TRC 20 with the name Bitcoin, but it is the most comfortable way for me to invest in BTC now, I can do it through this wallet.
Also I have seen one token called NFT. I want to investigate it and buy as well, as nowadays there is a hype around NFT, so investing in this sphere might be a profitable decision.
But TRX is still lacking critical mass in terms of projects launched on the network isn't it? I barely read about projects that get launched as a TRC30. I don't know that much about it, but I do hold a certain amount of TRX as I also fell in love with its transaction speed and the cost. That's just freaking amazing, but still, without projects running on top of it there aren't too many reasons for holding TRX other than using it for cheap and quick transactions.