I hate all these fukn chairs and desks, its nnot made for people who have long backs. I m always slouching in my chair and its affecting my ergonomics.

I work from a home office. I bought a big heavy old dining room table for my desk. It's probably 2" taller than standard desks.  I also use a lower chair.  It's an old leather and wood chair from a 70's legal office - the kind that clients sit it.  It has a very low back that only reaches up to my mid-back, but it works better than any office chair I've tried.  90% of it is lumbar support.  I then position my keyboard about 14" into the middle of the desk, so my elbows rest flat on the table.

Seems to work for me.  My wife is a certified workplace ergonomics specialist and she gives me crap about how wrong my setup is . . but it works.

I'm 6'2" and bought this La-Z-Boy office chair from Staples:



http://www.staples.com/La-Z-Boy-Nexus-Bonded-Leather-Executive-Chair-Black/product_1103523?externalize=certona

Best chair I've ever had.

I put my desk on 4x4 spacers.  A Herman Miller chair will work for you.  They aren't cheap, but buy once, cry once.  Mine is probably 20 years old and still works great.

I use a $99 chair from Costco that looks just like the Lazy Boy above. It feels great. Or...