I like different social networks for different reasons... but I have to say G+ is becoming one of my favorites.
I am mainly B2B so I don't do much marketing on Facebook (honestly its starting to annoy me lately for personal use too).
Twitter tends to feel one sided - I find it hard to keep up with posts.
LinkedIn I love for business groups and networking.
Google+ is starting to grow on me for professional networking - but I feel it is strongest for B2B.
My marketing page has grown nicely over the last few years - over 1,000 now - and I believe I am starting to see organic search lift from that. So, for those reasons I am becoming a bigger fan.
You can join my marketing page circle here: https://plus.google.com/u/0/b/114835964625426883708/