I'm finding some of the games in my library are less mouse+keyboard-friendly as others, so I'm considering buying a controller of some kind to go with it.

Anyone have any brands or types they particularly like that they would recommend? The ones I see online usually tend to have quite polarizing reviews so it's hard to tell if any are just universally decent.

Also I was wondering if an XBOX controller would work on a PC (or a MAC, but I doubt it)?

Logitech F#10 series. I use the F710 which is wireless, but the F510 is the same in wired, and the F310 is the F510 without the vibration. They also allow you to switch between XInput and Dinput, so you can use it for older games as well.
It does seem as if there's a bit of a deadzone for the sticks, but (for my gamepad at least) it seems that it requires a bit of movement to register the movement, but it then does respond to movement in the deadzone just fine.

You can get Xbox gamepads that specifically say on the package, "for Windows" and they work great on PC, but I'm not sure if they would work with a MAC or not. You can get them wired or wireless (with a USB dongle.) :)

http://www.macupdate.com/app/mac/24762/xbox-360-controller-driver
https://github.com/d235j/360Controller
http://www.instructables.com/id/Use-an-Xbox-360-Controller-on-OS-X-wired-wirele/

all wired xbox 360 controllers work on windows 7 and 8 with no extera drivers needed
and most pc games work with the 360 controller as well

as far as pc controlelrs the xbox 360 is one of the best out there

it isnt

i regularly switch my wired 360 controllers between my pc and the 360 itself and the controller just works on both platforms

there is a experimental driver for mac os X for the 360 controller but its not oficially supported

The only difference between Windows version and non-windows version of Xbox 360 wired controller is the absence of CD with drivers.

which you dont need unless your still using xp

vista 7 and 8 just install the controller automatically

I find X360 just fine. It works right off the bat with Win 7 and with most games, it is quite cheap and if you are familiar with it then there is little reason to go for something else.

Yeah, but in this case you can easily download it, so no problem.

Hmmm, maybe I'll just pick up a 360 controller then. Definitely worth looking into at least.

Hopefully it doesn't suffer the joystick deadzone some gamepads I've looked into are guilty of, as it would make precision aiming or slow movement kind of a pain if it does.

best option to be honest

80% of the current pc games released since 2006 work with
and have onscreen xbox 360 specific prompts

ive been using an xbox 360 controller on pc games for years now with no complaints

I personaly use a PS3 controler with a plugin, (not that motion joy malware) and everything is fine, but that's also because I prefer the dual thumbsticks of the dual shock better. I guess it depends on how you feel comfourtable, if you can try to get the gamepad in your hands and try it before buying.

I actually have a PS3 controller, so that would save me a little hassle.

Except, um... that malware... yeah, guess I should avoid that part.