Big N wants you to update your Wii to 4.3 so that they can block most homebrew.
Besides that, it comes with ios58 that has native usb 2.0 support.
You can install that ios58 without the upgrade to system menu 4.3 as well.
Once on 4.3, the bannerbomb exploit doesn't work anymore, so you need an exploitable game to mod your wii.
4.1 is a better choice than 4.0, so you might consider updating manually if that is what you have. 4.1 fixes a bug (it was the last release to offer features or bugfixes) where you see a WiiMotionPlus video when exiting a VC or WiiWare game (or something like that, it's been a few years).
It is beyond me why any guide on here would actually suggest updating to 4.2 as there is no logic to it.
Stick with 4.1, I doubt there will ever be any reason to go above 4.1. 4.1 does everything 4.2/4.3 does without the anti homebrew supplied by 4.2/4.3. You can update all your ios and channels with MMM, wii-mod, modmii, or dop-mii. Just update what you like to update yourself with one of those and never update from Nintendo. Also never update your system ios60 as the latest updated version is a useless stub. Never install stub ios files, installing a stub system ios will brick your wii. 4.0/4.1 runs on ios60-v6174 and ios60-v6400 will brick sm 4.0/4.1. When updating channels you also need to update the ios that the channel runs on, just don't fork ios30/50/60/70/80 as these are the most common system ios, no stubs.