I recomend just going with Nexus, I started out with workshop and still run some workshop mods alongside the Nexus mods I manually install. Two big benefits to Nexus imo: way bigger selection of mods to chose from & manually managing the mods allows for you to manage the mods you use far better and with a higher level of control than with Steam, sometimes mods just dont uninstall from the workshop (for me atleast) and never had that issue with Nexus. Downsides are that its less convenient to use (although really not that bad) and that you need to become familiar with the scriptmerger. Ideally you should use the script merger, filelistupdater, and perhaps even the Witcher 3 Mod Manager which is nice for the load order. I forgot the modname but you can also set up a mod that gives you in game settings for your mods so you can control some of them in game. Good luck!