Microsoft, Apple and Google represent the 3 major forces in computing for me, so a few of my thoughts on each might be appropriate here, rather than repeated on each application page.
I have yet to find any free alternatives to tempt me away from MS Office, including on the Mac. Perhaps it's the devil I know, but I find the usability and capability of Word, Excel, PowerPoint and Access unbeatable.
MS Internet Explorer has improved dramatically in the last few years, and is a very usable browser for Windows based machines, if sometimes intrusively cautious because of security risks. And if Bing tries to muscle in over Google one more time I'll ...
If you like computing the way Apple thinks you should, it has some great products and a great ethos, which may justify their premium pricing. My Macbook Pro and iPod Touch are a real pleasure to use.
OS X is a slick operating system, but with enough annoyances to give me a sneaking preference for Windows. Why can't it learn where I want to put my windows?
iOS apps are usually a bit better than their Android equivalents, but I wouldn't mind some widgets.
I don't use Safari much, partly to get more consistent browsing on both platforms.
iTunes, although bloated, is unbeatable for music and podcasts, both very important to me.
I use Mac Word for all my language work with fairly easy to remember keyboard shortcuts for accents etc.
I do like Mail on Mac, but I use Chrome web-based Gmail with an ad blocker for my main email account.
I now use Chrome on PC, Mac and Android for 90% of my browsing. Once you get used to its extensions and applications, it's hard to go back to a lesser equipped browser. I do use the others occasionally mainly to check consistency of presentation of my web stuff.
I chose Nexus 5 (Android) over iPhone 5 (iOS) partly on price, partly on size, and partly to check out Android, which I now prefer.
I have used Picasa for years to back up my photos and share them with friends and family worldwide. Google tried hard to subsume Picasa in the intrusive Google+ (their no-so-popular alternative to Facebook). They are now replacing Picasa with Google Photos, which is slicker but lacks some of Picasa's functionality. Since they stopped counting decent sized photos as part of your allowance, you can store in the cloud a lifetime's worth of albums for nothing.
Google Drive is great for people with a Google account, especially for audio streaming. Fortunately they now allow you to set up a free account using your existing address email, without Gmail, Google+ etc. but some people are reluctant to sign up.
Google Groups don't get much publicity, perhaps due to concentrating on Google+, but it provides a handy way to enable selected people only to access restricted material on Google Drive and Google Sites.
I chose Google Sites for my web sites. It's a great way to share language learning material, but the latest version still cannot match the capability of the "Classic" version.