>>1653030Others have already answered but with Shimano vs Sram - Sram makes it easier to mix and match components from different groupsets while Shimano has some proprietary anti-consumer solutions to make you pay extra for specific tools and parts. For example Sram GPX cranks only require allen keys to strip, Shimano Hollowtech 2 does that as well, but you need their shitty star key to undo that one screw - not available in most common cheaper toolsets.
MTB and road group components aren't compatible with Shimano past Sora brifters and old Deore mechs. GRX I think is more compatible, but also quite expensive. Also Shimano pedals have these dumb reflective plastic things sold separately, which smells of garlic from miles away.
On the other hand, Sram is less available and more expensive, so there's that and they disc brakes (pads) wear slightly quicker than Shimano. Also, for some reason there are shills here who basically say Sram is shit and it's probably due to the 1x is dumb meme, cause apparently not having a front mech makes you less of a man or something IDK.
In any case, there will be people telling you one is a meme and the other is shit or whatnot, but just get what works for you and is available while keeping potential repair/replacement costs in mind. They both work well.
Campy is road bikes only I think, hard to even see where I come from, super rare and super expensive. Also, Mircorshift exists and I hear it's gotten better, apparently it's quite cheap and works.