Wiring a switch for a light fixture

Then clearly the second option is the more preferable. :-)

It really doesn't make much of a difference, unless you might at some time want to install a device, such as a timer switch or combination switch/outlet, which needs a neutral, in which case you need at least three conductors (constant hot, switched hot, and neutral). That could be achieved either with two 2-wire cables or one 3-wire cable.

I would find 1) to be preferable. It allows for any future devices that require a neutral.

Are both methods allowed by electrical code? All switches I have seen are wires using method 1.

I've seen a lot that used #2, but almost never marked as they should be. I still prefer #1, which is more flexible.

According to peter :

Both methods are permitted. I've seen several DIY sources expressing a strong preference for (2), which makes little sense to me at all. I think they're just copying what they see electricians doing tract houses do. It's a bit faster, so it lets them do more jobs.

Method (2) may originally have been a carryover from knob & tube days, where the hot wire tends to route between ceiling fixtures with the outlets and switches tapped off it, and where there was less concern about multiple circuits (ganged switches on different circuits) being in the same box.

I _prefer_, and almost exclusively do method (1), but sometimes (2) works out better with a reno.

I don't like marking wires either ;-)