We have been buying from V4Ink for a long time. These are the best 3rd party toner suppliers we've come across (not the absolute BEST, but out of the ones we've tried, V4Ink has worked great for us). Cartridges interact correctly with printers. It had no weird spots or streaks and is quite long lasting. For the price, I don't think it's easy to beat.
Brother TN436BK Super High Yield Toner, Black - Retail Packaging
11 Review
HP 902XL Magenta Ink Cartridge for π¨οΈ HP OfficeJet 6900 & Pro 6900 Series, T6M06AN
11 Review
H&BO TOPMAE Remanufactured Ink Cartridges Replacement for HP 61XL 61 XL β Envy 4500 5530 5535 Deskjet 1000 1056 1510 1512 1010 1055 OfficeJet 2620 4630 Printer (1 Black 1 Tri-Color) - Enhanced SEO
13 Review
Cartridge NV Print CE285A for HP LaserJet Pro P1102/P1102w/M1132/M1212nf/M1217, black
13 Review