Sythis is a safe bet when it comes to an enchantress commander.

Calix is a good card for the 99 for sythis, but you can also always use him as the commander.

One that I haven’t played myself, but that takes a different approach to an enchantress commander is Eriette.

I'd recommend Tuvasa instead of Sythis. Access to blue gives you some interesting options and it's less boring than Sythis while still having plenty of options to draw obscene amounts of cards (e.g. using Sythis herself). That was my path, found Sythis to be too linear.