I use an adjustable office chair, although now that we've down-siized, it's a little bit of a tight fit in my bedroom, but it gives a lot more support than a dining room chair. I can still roll around a little between the sewing machine and where I cut and iron fabric, so I don't have to get up and down as often (tough on my arthritic knees) and it helps.

I use a stability ball to sit on when I am hand quilting. It's a great way to work on balance and core as well. It relieves a lot of back issues upper, mid, and lower back areas. It forces you to sit up in the proper position.

I haven't tried it at the machine.

Appreciate everyone's input. I have been trying to figure out which would be the best chair for me. Currently, I think something that swivels for turning from sewing machine to side table for pressing and cutting is essential. :-D

That's what I use and I prefer the ones without arms so I can get closer to my machine. And of course it's got to go up and down.

I have an adjustable office chair, it is a high quality brand with dense padding and many adjustments. I have to sit high to reach my machine which rests on a counter-top bought at a yard sale, so hubby is building me a foot platform tonight. Otherwise, I'll get back spasms and leg cramps from hunching over, and not being able to rest my feet on the floor.

IMHO it is all worth it. It is hard to concentrate on your sewing if your butt/back/legs, etc. hurt too much to concentrate! I also keep my ironing board across the room so I am constantly up and down.

I use a rolling office chair and I like it. I can just roll over to my ironing space and back to my machine. I have had back surgery and my back doesn't bother me one bit in this chair.

I just recently got a Koala studio and the chair that goes with it is wonderful! But before that when I had my machine on a table, I used an old office chair that was VERY comfy, The secret? It had a "tractor seat" which means there is a "hole" (really an indentation) where the tailbone hits the seat. It really helps!

I use an office chair with rollers.

I purchased 2 task (office) chairs at the local office supply store. One is at the computer table and the other one is my sewing chair. I have my sewing machine and serger sitting side by side on a 4 foot banquet table and roll the chair from one to the other. And it's comfortable enough for me to do hand work while I watch TV. I suggest you go to an office supply store and sit in a task/desk chair and see how it feels.

This was my first thought:-)
I sit on a computer chair, I bought a gel cushion for the seat and a back support that I was lucky to find in a $ store. I sit at my dining room table and sew. This is ideal for me:-)