Cascando
Furniture (Contract/Commercial)
Pineapple
Connection UK
Watson Furniture
Haworth
Davis Furniture
SIXINCH® USA
Frovi
I love their furniture so much. UK-based company. Sustainable (uses bamboo and sustainable fabrics - lists their CO2 footprint, certifications, etc). I've used them in a couple of projects, including their Bae, Bamboo, Relic, and Flord lines. Nice Revit files. Highly configurable.
Bejot
ERG International
ERG offers a wide selection of lounge and soft-seating furniture
Global Furniture Group
Knoll
KI
Kimball International
Nice rolling whiteboards and such
Corral Design
Humanscale
HON Office Furniture
Gunlocke
Martela
Task chairs, conference tables, phone booths and meeting modules.
Muzo
Poppin
Scandinavian Contract Furniture
Palmieri Furniture
Pair
Andreu World
DUM office
ENEA
Office Chairs
Extremis
Forma 5
Arper