The principle of most L2s is to have lower and faster transaction fees
Some have other features more geared towards DeFi, or NFTs etc
But what I like to point out is that some L2s have a high TVL because of users farming airdrops, like the Base network, Linea, Optmism etc
There's a lot of movement because of this, lots of bridges happening trying to get airdrops from bridges too, like Jumper, LayerZero, DeBridge...