MCP25625 LoopBack Mode Reponse
I'm using this controller.

Did you put the controller on normal mode after configuration?
Are you able to transmit to other nodes when using the normal mode (no loopback).
What is your message ready signal? An interrupt pin? Are the interrupts correctly configured in the controller?

Please check that every step in your configuration is sucessful, if you want more help post your configuration steps.

I don't have access nor experience with a MCP2210, so I cannot help with it.

PD: I don't recomment this CAN controller. The datasheet says that the filters are not available when listen only mode is used and that in this mode the controller passes all messages, including corrupted messages.
I found that the filters work on listen only mode but the controller still accept corrupted messages (I tested sending messages with different bitrate).

If you want to build an USB to CAN interface better look for a microcontroller with USB and CAN peripherals, the STM32F105 or STM32F042 are good choices.