I have 4 of these in my house and they are great. I use them exclusively with homekit Nd have no issues with them most of the time. You randomly get a connection issue, but a quick turn off and on at the switch solves it. I have figured out that it might not be the best idea to replace all my lights with the. I mainly use them in areas we commonly turn the lights on and not the bedrooms. Just the hallway and kitchen (which is also shared with our lounge room). This works well for as as I have programmed the lights to automatically turn on and off at certain times of the day. This have been extremely useful.
I see what a few people have said about the fact that you need your phone with you. But I wear an Apple Watch and this makes it easy to turn on and off the lights and I normally have my phone with me. You have to get used to it and may have to really think about the best place to put them. We also have lights that we can still turn on and off normally, so that helps.
So my recommendation is not replace every bulb and be really strategic on where to put them.
In terms of the LIFX bulbs, I highly recommend them. They are cheap enough to get you started on making your home smart as you don’t need a hub and you can get one to try out. This is what I did and I quickly purchased more to cover the areas I wanted too.
I can’t speak for Google Home or Alexa, but I have found them to work great with Homekit.
My one recommendation is to use the LIFX app to set your schedules, it found it more reliable than HomeKit for that. But for setting scenes, turning on and off and setting brightness, Homekit and Siri works great.