Owned a Pebble for like 3 seconds. Yuk on just about every aspect. (Bought sight unseen on Kickstarter. Sold it literally hours after receiving).
Never owned a Vivoactive, but have used a Fuelband and Fitbit Flex, Force, and Charge HR. For someone who needs digital shaming to get off the couch, out of the office, etc. activity bands are great IF you give them that power over you. So you still have to be motivated to do the hour walk or quick jog or whatever.
The AW, of course, has a Fitness app which is very similar to what the Fuelband was. The Charge counts steps climbed, the AW does not. The AW can do a heck of a lot more than the Charge, of course, but at 3x the price. The AW has to be charged nightly. Most activity bands can last a week before needing charging meaning you can keep them on 24/7 and all your moving around the house is counted more easily.
Personally, I "graduated" from activity bands into a full fledged running watch (Garmin 620). I use it exclusively for running and then switch back to my AW afterwards. The AW can't compete IMHO with a good sports watch because its a "jack-of-all trades, master of none. I wear the AW mostly because I like notifications and Apple Pay is convenient where available.