I use a lot of the technologies, currently my house runs several automations via the Echo, Wink Hub and Apple TV as HomeKit hub. Apple typically is early on the talking, late to the show, but they also tend to focus more on the customer experience overall and their security. You can buy hundreds of options in terms of IOT devices, but unless you do research on their backgrounds, you're also quite possibly buying something that is generically designed by one or two large market players, and re-branded under whatever brand you bought.
Ultimately it does matter with getting things to market, but as more and more IOT devices get compromised, and more and more people realize security needs to be a forethought versus an afterthought, we might see some more shifts in the future.
As for number of devices that work with HomeKit or not, a lot of products add in HomeKit support via alternative bridges, so it doesn't really take redoing everything, but rather adding a piece of equipment that makes it compatible. My chamberlain kit in the garage did that to add HomeKit support. HomeKit was able to fix what Chamberlain took away from it, which was also my core purchasing reasoning, which was to schedule it to automatically close my door by 9PM every night. Chamberlain broke something in it, making it so scheduling didn't work anymore, and they broke the ability of the Wink Hub to close it also on a schedule, but HomeKit allows me to achieve it. To me that function is crucial, because for some reason we just forget to check the garage door at times, and nothing is worse than waking up in the morning and realizing your garage was wide open the entire night.
I guess really my point is, ease of integration is definitely a key part, but shouldn't be the only thing. Security of IOT devices needs to matter, not just that it works with everything. I would probably opt for either old school X10 in a new build or Apple personally. I like my current setup, but ultimately i know that Amazon wants my money and wants to know what i would buy so they could sell it to me, Wink is now owned by Will.I.Am and while i have seen considerable upgrades and enhancements since he's taken over, he could still just as easily run it down the drain.