Just a quick rundown of the four most common switch types to help you decide:
Blues are somewhere in the middle of the mechanical switch spectrum in terms of stiffness, so there are lighter switches that can help with your stamina. But they make a tactile, audible click when pressed, which benefits your accuracy. But I personally wouldn't recommend them unless you plan to pick up another mechanical keyboard down the line, as they make double-tapping more difficult by design (which slightly sacrifices the consistency of repeated presses in order to make the feedback more tactile).
Browns are on the lighter end, but the tactile feedback isn't as tactile nor as loud. It is still there though, so it will still help a bit. And it doesn't have the double-tapping issue that I mentioned about the Blues, as the design of the switch is different. The only real negative that it has is that it isn't as light as Reds, nor as tactile as Blues. It's somewhere in between.
On the other hand, a lot of players seem to recommend Red switches (at least for standard mode), which are the lightest you can get. They're amazing for stamina, but they have no tactile feedback at all (aside from bottoming out, but that won't help your accuracy much, as mechanical keyboards actuate at the halfway point), so I'd be reluctant to recommend them for osu!mania. I've also heard people say that the lightness makes it easier to make mistakes when typing, so that might be something to consider.
There are also Blacks, which are the stiffest out of the popular four. They're just like Reds in that they don't have tactile feedback, but the high resistance could potentially make your fingers lift faster and allow you to stream quicker. But they're the most demanding on your stamina, so I wouldn't recommend them unless you have strong fingers.
Overall, I'd personally recommend Browns as a good all-around switch. It's what I use, as well as a few top players of other rhythm games. But it's really up to you to decide which switch you'd prefer, as each one has its benefits.
And regarding the two that you linked: You can get both of those keyboards with your choice of switch, so the only real difference is that one has a number pad and the other one doesn't.