As an investment Facebook is a no brainer, the revenue growth coupled with decreasing expenses. They project that they'll be spending much more each quarter and thus earn less but yet can't spend enough to keep pace with all the cash they have coming in. Instagram stories was a home run for them and I'm sure they'll do a great job monetizing Whatsapp as well.

Personally I use all their apps. Facebook, Instagram and Whatsapp. I don't post much, but I find them great for direct communication and to keep up to date with major events in your network. I use the "see less from..." filter heavily to weed out the frequent posters.

If they ever decide to launch a crypto, its competition wouldn't be Bitcoin, it'd be the US Dollar.