Some older consoles have very negligible size libraries in modern day terms, and who knows what sources of ROMs will be taken down by lawsuits in the next few decades. I feel like there is some sense in making a complete archive of a systems game library, but for my personal use I usually just download / dump / rip what I need specifically.

Whatever file format I use them in is also how I back them up, I backup my entire desktop’s and laptop’s data to an external hard drive and an online service provider. I’m sure a compressed format would be more space efficient but that would take much more time given my use case.

In the case of my laptop it runs Linux and the filesystem I use supports “transparent compression” (almost all contents of the drive are compressed with zstd), so I’m guessing any of the ROMs on there will have already been compressed as nuch as they can (but I’m not knowledgeable enough on the file format specs)

I mostly play rogue likes with controller and would like a XBox/Playstation style controller

I’m assuming you dont need gyro or touchpad that you’ll get with PlayStation / Nintendo compatible controllers, however if you do want those features the Switch Pro controller & the DualSense (PS5) play nicely on my Linux computer (with steam)

Out of the two I’d probably recommend the dual sense since you’re used to Xbox / Western PS layout rather then Nintendo / Japanese PS layout.

I’ve heard good things about the 8bitdo controllers, but can’t comment on their compatibility or quality. The contemporary xbox wireless controllers I don’t personally like, the current ones have this extra grippy texture on the back and thumbsticks that doesn’t sit well with me and the lack of rechargeability ootb is disappointing for the price.