Totally depends on your budget!

Salwa Road (You can find some luxury designer brands and bathroom/kitchen fittings.)
Home Center in City Center, Centerpoint/Al Asmakh Mall, and Musheireb.
Homes R Us in Hyatt Plaza.
Bo Concept in City Center.
Souq Al Haraj in Najma area.
ID Design in The Mall.
Origins (www . originssofas . com)

I usually end up buying from Home Center because it's relatively inexpensive, and at times I take things apart and customize them.

Some of the couches in ID Design are very cute, colorful, modern and at a decent price if you are looking for something nicer than Home Center.

But Doha still lacks a great basics store for furniture. That's why everyone is waiting on Ikea.