Apple - Nothing.

Google - I make heavy use of Google's services. Maps, YouTube, Search, probably a few more I can't think of right now. I guess I could use Bing for Maps and Search if I really had to (it would pretty much take a gun to my head to make me do it, though), but I don't think there's any suitable replacement for YouTube. I'm -- grudgingly -- using Chrome, as much as I dislike it (I still miss Opera 12). One of these days I'll dump it entirely in favor of Pale Moon. All my TV/movie purchases and half of my book purchases are on Google Play. I can get them from other sources, but I'd be pissed if I had to re-buy all my stuff because I abandoned Google. I have an Android phone. I guess I could use an iPhone if I had to (like Bing, it would take a gun to my head to make me actually do so), but I already paid for a ton of apps and I'd hate to re-buy them. I wish Maemo was still around because I still miss my Nokia N900; a return of Maemo on cutting-edge hardware is the only thing that could get me to voluntarily leave Android. I have a Nexus 5X and use Project Fi; switching to another carrier would suck, but I could do it. I make extensive use of Project Fi's SMS-via-Hangouts, so I'd only leave Fi if I had no other choice. My company is a G Suite shop, so even if I got Google out of my personal life, I'd still have to use it at work. I wouldn't be surprised if some services I use make use of Google Cloud.

Amazon - I'm a Prime member, I prefer Amazon when I buy stuff online, but I only shop online sporadically. I could shop somewhere else, though I like the convenience of just going to amazon.com and typing in what I'm looking for. I buy stuff on Kindle occasionally (which I read on my Android phone, not on Amazon hardware), but I actually prefer Google Play Books. I tried Amazon Eats once: the driver got lost, he was a half hour late, and my food was cold; I'll stick to Eat24 and DoorDash. I deal with AWS at work; that's going to be harder to replace, but it's not my call. Lots of services I use make use of AWS as well.

Facebook - This is how I keep in touch with most people in my life. There's no suitable replacement. Messenger has become the only instant messenger outside of work (mostly Slack, occasionally Hangouts in G Suite) and talking to my parents (Project Fi's SMS-over-Hangouts). I have an Instagram account, and I've tried to use it, but I'm just not interested, and all my friends who post on Instagram have it set to auto-crosspost their photos to Facebook, so I'm not really missing out. I have never touched WhatsApp and never will.

Microsoft - I own a Surface Pro 3, and I enjoy the Windows 10 experience on it. I have an Office 365 subscription, but I don't really use it (it came with my Surface, and I renewed it last year because why not). My desktop dual-boots Linux and Windows, but I only boot into Windows for games, and a lot of the games I play are either cross-platform or on consoles, so I don't boot into Windows often. I used to use Skype, but that was mostly for work; I don't work at that company anymore, and I use Facebook Messenger to talk to anyone there I still want to keep in touch with. I use LinkedIn as an online resume. I personally don't care much about it, but it might hurt my career if I had no LinkedIn profile at all (this is purely speculative). I wouldn't be surprised if some services I use make use of Azure.