We've been with Segen from the start, we use other suppliers too but we get a decent discount off decent prices and their service is pretty good too. We've always had our increases linked to monthly spend , they reward loyalty and you have access to the portal 24/7 which is dead handy. They were the last wholesaler to reduce their credit limits and the first of the ones I dealt with to be re-stocked.
They aren't perfect, but anyone who supplied marginally cheaper provided the most appalling service - I'll be sticking with Segen for the forseeable.