We have both Up (by Jawbone) bands and Fitbit Flex bands. We've had Up for over a year, since well after the second generation came out and solved the unreliability of the original, and we're now on the current 3rd generation Bluetooth-connected Ups. And the Fitbit all have the same essential internal mechanisms, so the Flex, Force and One are basically the same (only the Zip doesn't have the sleep monitor function). We also both tried the Nike+ Fuelband SE. So we might have some worthwhile commentary.
First, we abandoned the Nikes because they're far more sports-oriented than general activity; no sleep monitoring. The advantage they did have was a clock display.
Up and Fitbit are very close in functionality. Up's battery seems to work a hair better; Fitbit's online dashboard is much better than Up's mobile-device-only access to the data, and its Bluetooth connection has yet to be dropped, unlike Up, where it's fairly frequently requiring re-pairing. But neither Fitbit's sleep monitoring nor its food intake monitoring is as granular as Up.
Since you have Fitbit, ENJOY IT! It takes getting used to to remember to set it to sleep mode and even more getting in the habit to remember to take it out of sleep mode in the morning. We both thought the sleep monitoring would be so-what after years of "controlled" sleep patterns, but we both admit it was eye-opening. Also, USE the food intake function. Although for one of us it was a great tool to contribute to getting back into shape, we both found it very illucidating to see what we've been eating with the Fitbit app and tools. And the activity monitorning is a similarly great tool if your goal is to improve your fitness. It also really is waterproof: it goes into the pool or ocean every day, and it goes in the shower multiple times every day, so don't be leery of that.
Feel free to email if you want to bounce anything off us as you're getting used to it.