Depends on what you want out of it. The RetroTINK 2X (Maybe needs a more distinctive name, cause the regular RetroTINK is a RasPi hat) only does passthrough, line-doubling 240p and 480i to 480p, and simple smoothing and filtering; so, if you’re going to run that directly into your TV, it’s up to your TV to do scaling, and some people might be annoyed with having to switch to a different input than the one their OSSC is on.
If you run it into the OSSC, you can use it to process the image in the same way you would for your other consoles, including Line 2x/3x/4x/5x; scanlines; and any sort of timing adjustments.
If you already have an OSSC integrated into your gaming setup, or plan to do so, it may be more desirable to run those legacy consoles through the OSSC for simplicity’s sake, so getting your setup up and running is more standardized. For example, I prioritize ease of use; ideally, I’d like to be able to switch on my home theater receiver (which would turn on my TV with HDMI-CEC), flip a switch on a PDU to turn on my analog AV equipment (including OSSC), and then just turn on whichever console I want to play–my setup should automatically switch AV to bring up the console I just turned on. This is entirely feasible with some of the boutique automatic switches and the right cables and devices.
Now, if I plugged one or more RetroTINK 2Xs directly into my TV or receiver, I’d have two separate processes for getting my consoles running. Personally, I don’t want to have to memorize or figure out, or make my girlfriend do so, how to futz with the AV equipment just right to get a particular console running; I just want it to be as simple as possible.