We use Softchoice (https://www.softchoice.com/?). I work at a Fortune 100 company. I don't have much to say besides that I haven't had many complaints, and I only use them because they were an approved vendor before I started, but I've had no issues with them. I mainly use them for mainstream products such as Jetbrains so I cannot speak to their availability when it comes to more esoteric licenses.