Fitness bands are the biggest selling wearable tech devices on the market and there are two companies clearly leading the way: Jawbone and Fitbit.
While the Jawbone UP3 and Fitbit Charge HR are the big name bands we're waiting for in early 2015, there's some great deals to be had on the previous generation Fitbit Flex and Jawbone UP24.
Essential reading: Fitbit Charge review
But if you're looking for a cheap fitness tracker this Christmas, which one of these two wearable stalwarts should you buy? Read on to find out…
Fitbit Flex v Jawbone UP24: Design
The Jawbone UP24 is coated in a rubber finish that protects a resistant but flexible core and, with the range of colours in the Jawbone line-up, there's something for everyone. It springs around your wrist, rather than being attached, and comes in three sizes – so you can make sure you get the perfect fit.
It's also water resistant, so you can take it in the shower, but it probably won't survive a dunking in the bath.
Essential reading: Fitbit Charge HR vs Jawbone UP3
The Fitbit Flex band itself is just a piece of plastic; the lights you see adorning the face actually emanate from the Fitbit core, a small module resembling the Fitbit One, which slots inside. It can easily be taken out, and you'll need to remove it when it's time to charge. Like, the UP24, it's also water resistant.
The Flex band comes in a rainbow of colour options meaning you can mix and match to fit in with your wardrobe. The clasp on the band strap is secure and should stay in place even during rigorous exercise.
Fitbit Flex v Jawbone UP24: Display
With no display apart from those lights, interaction with the Fitbit itself is pretty basic. Unlike some of the competition you can't keep tabs on things like calorie count or steps on the Flex itself; you'll need to fire up the companion app to delve deeper into your vitals.
Tap twice and the lights will tell you how much progress you've made towards your goal; tap five times to tell the Flex you're about to catch some Zs to send it into its sleep-tracking mode.
Guide: Fitbit Flex tips and tricks
Like the Flex, Jawbone has gone without a display for the UP24. Instead there are two LEDs that show you when you're in active and sleep modes and a single silver button that lets you flick between snoozing and waking. Like its Fitbit rival, you'll be using the partner app a lot.
Fitbit Flex v Jawbone UP24: Features
One of the Jawbone UP24's best features is its vibration alerts. These can be set to give you a buzz when you've been sitting still for too long, or when it's time to do a scheduled workout.
There's also a gentle alarm to wake you up when you're in your lightest sleep, which should mean you easily wake feeling refreshed, rather than bleary-eyed, because you're closer to a natural waking state than when you're in deep sleep.
Essential reading: How to buy a fitness tracker
In sleep mode the Fitbit Flex's sleep tracker will monitor how well you've been snoozing and there's a built-in vibration alarm to wake you gently.
Sadly the Flex isn't smart like the Jawbone UP24, with its light-sleep wake function - instead its alarm just buzzes you back from the land of nod at a specific set time.
Fitbit Flex v Jawbone UP24: Tracking
Using its built-in accelerometer, the Fitbit Flex monitors your footsteps and uses that count to calculate your distance travelled, your calories burned, and how many minutes in the day that you've been active. That information is synced with your smartphone over Bluetooth, without the need to plug the Flex into anything.
A nice feature is that your Flex can tell when you're moving with more intensity than usual and it will adjust the results to reward you accordingly. The lack of altimeter means it can't tell when you've climbed stairs or you've walked up a steep incline though, which is a shame.
In terms of accuracy Flex is pretty much on par with its rivals, though it's also easier to fool into thinking you've done more work than you have with a few sneaky shakes of the wrist – but why cheat yourself?
Wareable picks: Best activity trackers under £50
The Jawbone UP24 also tracks walking, running and sleep, and, as you go about your day, your steps, distance and calories are tallied up, giving you a total by the time you're ready to turn in for the evening.
When it comes to accuracy, we found the tracking on the UP24 to be quite a bit better than many of its competitors but roughly on a par with the Flex. If you do find the band is counting extra steps you can also calibrate it, which should set it right.
Fitbit Flex v Jawbone UP24: App
Both Fitbit and Jawbone offer third party app integration with the likes of RunKeeper and MyFitnessPal. If you're already using these apps this is a nice extra as it helps to create a more complete picture of your fitness and lifestyle.
The Fitbit app is easy-to-use, if a little uninspiring. The dashboard provides an overview of your steps, calories and so on, with access to a more detailed breakdown for each section after a quick tap.
If you want a detailed analysis of your lifestyle, the Flex requires you to enter a lot of your activity yourself, which is a little irritating but something you'll want to do if you want your Flex to be more than a glorified pedometer
Doing stuff like adjusting goals and setting alarms is simple and you can also easily log your food intake by taking advantage of the app's barcode scanner.
Must read: The top fitness trackers available to buy
The Jawbone app looks good and, despite the number of layers, isn't complicated to use. Each time you open it up you'll see a graph of your overall progress, with a minute-by-minute breakdown to show you exactly how active you've been throughout the day.
You can also log activities with swimming, yoga and a few other favourites are present and correct. You can also set your overall movement and sleep goals if you find yourself easily beating your targets, as well as setting more minor ones.
Fitbit Flex v Jawbone UP24: Battery
You can expect get between five and seven days out of a single charge of the UP24 - it's just a shame that you'll need to use the proprietary charger (which uses a 3.5mm jack) when it's time to energise that battery every time it goes flat.
Essential reading: Jawbone UP3 everything you need to know
The Fitbit Flex charger is perhaps even more fiddly as you'll have to pop out the module and pop it into a separate charging pod. Once charged you can expect to get between five and seven days of use on a single charge; matching the Jawbone UP24 and surpassing many others on the market.
Fitbit Flex v Jawbone UP24: Verdict
If you're on the prowl for an activity tracker, the Fitbit Flex won't let you down. It is a well-balanced choice featuring a simple design and some solid tracking features - not to mention an affordable price at under £80.
Read our full Fitbit Flex review
However, despite its more expensive price-tag (£124.99), the Jawbone UP24 shaves it thanks to its super slick design and enhanced features. It's comfortable, comprehensive, and a solid choice for anyone looking for a fitness tracker that's a great all rounder with more than a modicum of style.
How we test
By Paul Lamkin
Wareable Media Group co-CEO Paul launched Wareable with James Stables in 2014, after working for a variety of the UK's biggest and best consumer tech publications including Pocket-lint, Forbes, Electric Pig, Tech Digest, What Laptop, T3 and has been a judge for the TechRadar Awards.
Prior to founding Wareable, and subsequently The Ambient, he was the senior editor of MSN Tech and has written for a range of publications.