This is a somewhat loaded question, and if you ask each person working on SundaeSwap why they choose to, you'll likely get a different answer each time.
Since the answer to this might by itself be a research paper on its own, we can break it down to two key points:
Cardano currently has one of the largest communities in crypto. With over 600k subscribers on Reddit, 1m+ followers combined between the 3 core entities behind it (Emurgo, Cardano Foundation, IOG), ADA being currently ranked among the top cryptocurrencies by market cap, and the fact that at the time of writing this 70% of ADA is currently being staked, it means Cardano is one of the most popular blockchains.
For dApps, adoption is everything. Having a large community that already is technically savvy and confident enough to transfer their funds to a non-custodial wallet makes it easy to get an initial surge of adoption!
Cardano is built utilizing the Extended Unspent Transaction Output (eUTXO) model. This sounds complicated, but to simplify things a little, you can imagine it working similarly to how Bitcoin operates. If you send an order, it will be queued up among the other orders and be executed in the order it was sent.
This is in contrast to an account-based model (think: Ethereum) where orders are prioritized based on the amount of gas each person pays. This creates problems where transaction prices skyrocket (as the price of ETH goes up, tx fees go up, and as ETH becomes more popular, more people are competing for space in a block, driving prices even higher) and can even fail. This means that in certain circumstances your order can fail to go through but you still get charged crazy amounts!
Other chains have gotten around this by simply centralizing their chains or making it extremely expensive to run nodes (in a sense, centralizing the chain). A blockchain can become extremely fast and cheap to use if the people developing it choose to just run nodes that validate transactions themselves, or carefully choosing the people that are allowed to do so. While this might not seem like a problem at first glance, this creates possibilities for censorship and attacks on the blockchain.
In the future Cardano will be decentralized (anybody can run a node), proof of stake, and extremely scalable (think: tx speeds measured in milliseconds, with fees in the pennies), and along with it have the architecture to support layer 2 solutions for governments such as decentralized identities (DIDs).