Having an actual MIDI output (instead of USB MIDI) is a good thing, because this allows you to connect devices without a PC inbetween.
Rack-mount modules (e.g., Motif-Rack XS, Integra-7) are large, and correspondingly costly, but there are also "desktop" modules, such as the Mobile Studio Canvas. It might be cheaper to buy some used, discontinued model (e.g., SD-20/50/80, SC-8820/8850, SC-88(Pro), MU500/1000/2000).
Using a PC/laptop is always possible (with suitable software), and switching tones through MIDI will work if your keyboard has the controls for that. However, even with a good sound device (that has good drivers), latency can never be as low as with a hardware module (whether the difference matters for you is another question). Furthermore, a general-purpose machine always will have software/configuration problems, and might not be available when you feel like jamming.
Answer from CL. on Stack ExchangeAdvice for MIDI keyboard to start learning music production ...
What’s the best budget midi keyboard for making music?
Best MIDI (Full Keys) Keyboard-Controller for under USD $300? - Steinberg Lounge - Steinberg Forums
Best 88 Key MIDI Keyboard on a Budget?
do you need 88 keys? unless you're doing classical you probably won't need it and it saves desk space i have the Nektar Impact one and I love it but don't use abelton
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It’s just so annoying, coming up with amazing ideas while playing piano, but not being able to properly record them So I’d love to have some type of midi keyboard so I can directly play into BandLab or whatever. I would really appreciate if someone could give me a good BUDGET option. Thanks!