If we're talking about use cases beyond lights, timers and reminders, the biggest issue I see with these systems right now is the hallucinating / sycophancy. It's embarrassing / dangerous for those who don't understand and accept it's happening, annoying / limiting for those who do and have a working knowledge of the information they're requesting, and a business risk for those who develop and deploy these systems for business purposes.
Let's say Apple somehow solves that before everybody else - that would make Siri arguably better than the others. Apple might even be the most incentivized party to figure it out since it has a much more "premium" image to uphold, while its competitors are more interested in moving fast. I bet Apple would really like Siri not to become a lying piece of poop on top of its other charming qualities.
At the same time Apple's past performance doesn't fill me with confidence, and its only saving grace (in my eyes) is that the others keep failing on this aspect. Who knows how long that's going to be the case.