I also have Alexa setup with Hue, and I find Siri requires a lot less rigid phrasing than Alexa and is better at figuring out what scene/color/brightness level/etc you actually wanted. But since my Echo dot is always on the kitchen counter, Alexa is more convenient.
I've got an Alexa dot and a Google Home right next to each other. I also find Alexa's commands especially rigid. But "Hey Google" is a guttural sound that's almost a tongue twister and the mic's aren't as good so I stick with the Alexa for hue.
