Best ball chair 2012

Customer Reviews 
Gaiam Balance Ball Chair (Black)

The chair is surprisingly comfortable. I'm not sure how *much* it helps me with balance or toning, but I do actually feel like I'm using my muscles a little more than usual while sitting all day at the office, so I feel pretty good about it. And it looks really nice, too.
Overall I like the chair a lot, just one real complaint. There is no height adjustment. For me it's not much of an issue because my desk happens to be at around the right height. But this might be a problem for someone else. I suppose you could let some air out of the ball to make it a little lower, but that doesn't strike me as an ideal solution.
I do have one suggestion for anyone buying this chair. There are four wheels that you snap into the proper places onto the bottom of the chair when you're assembling it. Two of the four have locks you can flip down to prevent the wheels from rolling. I have found that with these two wheels attached on the front side of the chair, my feet keep accidentally hitting the locks and activating them so that it's difficult to roll the chair. I'd suggest putting these locks on the back side of the chair unless you plan to leave the locks activated most of the time.

Customer Reviews 
Fit-Chair 40090 with Base

I was having a lot of lower back problems due to sitting in a chair all day at work. While getting up and moving around more often is important, it is hard to do when you have more work than you can keep up with. This balance ball chair makes a world of a difference by helping to keep my core in motion even while I'm sitting. I originally tried a regular balance ball, but it was difficult to use without the wheels. This chair is the best of both worlds, giving the added motion of a balance ball, and the mobility of a chair with wheels. It didn't come with the bar that is shown in the photo to hold the ball in place, but it isn't required since the ball stays put in the holder without it. Some reviewers complained about the height of the chair, but as it is a balance ball, the height is easily adjustable by adding or releasing air. I am 5'4", and was able to fill it to a perfect height for my body and desk.
I would've rated this chair 5 stars, but I'm very annoyed by the locks on the wheels. I've never had a chair with locking wheels, so I don't know why they felt they were needed on this one. I accidentally close the locks with my legs several times a day, and have to keep unlocking them because of it. If it wasn't for these locks, it would be the perfect office chair.

Customer Reviews 
TKO Anti Burst Fitness Stability Ball (65cm)

This is the ball that replaced my office chair at work. I sit on it daily, frequently bounce on it when no one is around, and it has rolled around my floor with coworkers a couple of times. I've only inflated it once (the initial time) in the time I've had it -- over three months!! I weigh about 130lb (+/-) so I don't add a *ton* of constant weight on the ball. It has lost *some* air (it's not perfect after all), but it's still very firm. (I will probably re-inflate it this week or next.) Three additional bonuses about the ball: (1) since it's a dark color it doesn't pop out at people as they walk by me at work; (2) it's neither sticky nor overly smooth; and (3) it's anti-burst. The ball has a good texture that keeps you in place but doesn't pick up lint/dust. Some balls seem to attract it. Also, if you've seen that episode of "The Office" ([...]) you can appreciate the importance of an anti-burst ball. I haven't tested out this feature (and don't plan on it!), but I am glad that it is there since ANY stability ball can be popped.

Customer Reviews 
Ball Chair Deluxe in Black

Before I say anything negative, let me admit that the product pretty much performs as advertised. It has, in fact, improved my posture and made me use my lower back muscles when sitting. However, other exercise ball chairs do that too and you might want to consider them instead.
My primary beef with this chair is that the armrests are inexplicably low. They actually fall below the tops of your thighs and poke into them. In fact, the armrests are so short that my elbows are a full five inches above them. At first, I thought this was because I am tall and the chair is quite small. But then I realized that the armrests would poke into your thighs no matter how tall you were because your seat would be at the same level regardless.
Look closely at the product photo. Yes, the ball will give somewhat under your weight, but not enough to get the armrests above your thighs, let alone up to your elbows. Despite appearances, that backrest is apparently supposed to support your lower back - not your upper back. That's fine: Lower back support is actually more important. But the designers must have forgotten that fact when they made the arm rests so much lower. The result is a sort of trompe l'oeil.
I can't believe this product made it past the development stage without someone catching this. Shouldn't someone have, you know, actually *sat* in the chair before putting it into production? Unless your knuckles drag the ground when you walk, there is no way those armrests will work for anyone, regardless of height.
Then there's the assembly nightmare. Apparently, the manufacturers don't believe in washers. Instead, they dab some hard plastic paint on the screw threads to serve the same purpose. Unfortunately, they a) sometimes use too much and submerge the threads entirely and b) don't believe in providing any spare parts. This meant I had to go at a few screws with a knife to make them usable. Again, somebody wasn't thinking.
After some consideration, I decided to keep mine rather than send it back. I just left off the armrests. It's obvious that they're missing, so it doesn't look terribly professional; but this chair is for home, so that aspect doesn't bother me. Also, it gives it a more industrial look, which I like (but you might not). To me, it both looks and feels better this way. For one thing, the armrests aren't poking into the sides of my thighs. For another, the armrests make the chair look child-sized even though the seat level is definitely at an adult height. Without them, it both looks and functions like an adult-sized stool.