My alternatives, I don't use or require some of the other apps
NewsBlur - Bing News is brilliant, also Magnify Beta makes flipboard look so boring
Google Hangouts - I use viber, simply because everyone else i know does to, be it if they are on iOS or Android or even your PC
OneDrive - I use this all the time to backup photos automatically, also for gpx files and all kinds of word, excel and powerpoint stuff
Google Play Music - I tend to use Amazon as most of the time its cheaper and can easily be shared across my devices
Out of Milk - I use Evernote, as you can create a list, note music/voice clip and its simply syncs to my Ipad and WP
Facebook, Instagram, are very well integrated into WP, I don't use Pinterest
Twitter - in my opinion is far better and quicker to use as its integrated in WP
I'm learning and stumbling my way about the Windows Phone world, coming from a fully dedicated Android background, OK I miss a few games and some of the apps are not quite so feature rich, but they are coming and development is building, to be honest its so much more exciting each day discovering new or favourite apps arriving in the WP Store, I find I use Facebook and Twitter more than I ever did with both iOs or Android as its seems more integrated and part of your everyday WP life.
Now just today one of my favourite Android games has appeared Darts Match and it loads fast and plays perfectly...
I am becoming a WP bore, With Android my life was taken over with constant tweaking and ROM flashing, forever messing about, never happy with my widgets, always changing my launchers and actually not really doing anything constructive or social, with iOs I never really knew why I bothered its just too staid and tedious, great way to nod off, stare at the iOS screen, the Ipad is great for my gaming needs, but that's about all its good for.