Well because we have a working product that actually exists and has been used for many years. Obviously it makes no sense to support a crowdsale without a product... people shouldn't be getting money without actually doing hard work. And as for SYS there is many threads talking about that... to be honest there is no comparison. BitBay has many more features. In fact we have a "wall of features"  https://bitbay.market/wall-of-features

That wall isn't even the full list either. We have exotic spend like freezing, switches, hash puzzles and time locks fully integrated, notary with notifications, tons of features under the hood and the cash for coins template.

Unlike other projects we are not limited to sales of goods, unbreakable contracts have extremely strong use case in employment, barter, cash for coins, and any type of contract you can think of.

And this is by far the main advantage. We don't have escrow and SYS does. So does Open Bazaar. Escrow is a very dangerous and weak system responsible for a majority of theft and loss seen today. Like on many E-bay scams the buyers or sellers get hurt when a product isn't as described, damaged, or an empty box. The arbiters must guess as to who is right and they commonly punish innocent people. Our contracts are a two party escrow system where both parties put their funds in a joint account and if they lie to each other they lose.

We were also the first smart contracting platform in the world before Ethereum (BitHalo) and the first decentralized markets and will soon most likely be the first moving peg. And that peg is also another major advantage which is an entirely separate subject.