personally i prefer numpad because sometimes the f keys are used for other things already, like video capture etc.
Edit: so I usually end up changing some of them. also the ones which have only ctrl + a button i usually change to ctrl + alt or such so that i dont accidentally trigger it.
On one hand, F keys are assigned to other stuff and it would conflict sometimes. On the other hand, people without numpads has to resign the keys every time. I need some data on what side has to resign the most keys in order for me to make an informed decision.
Most games use the f1 keys for console and other menus like that, none of the games i play make use of the num pad. I remap most tools I use to use num pad because of that.
I bet you could get some good data if you impliment that and monitor what the users choose. Although at that point the data might not be worth much anymore.
I concur with @Frostive, I use a Razer BlackWindow Tournament Edition that doesn’t have a numeric keypad. I can use the app, but it would be nice to be able to choose either way. Unfortunately, I don’t have a lot of space on my desk.