Vclaw
2
This does depend on a number of things.
Firstly, what OS are you using? If using Windows, then Maperitive is probably easiest to install and use. I think you can also use Maperitive on Linux if you install Mono.
Whereas Mapnik can be rather complicated to install and setup. I think it is getting easier in Linux, as you can just install most things that you need from the package manager. And there are some useful tutorials for it. Its probably more complicated to install Mapnik on Windows.
How large a map do you want to make? I think Maperitive has to load all of the OSM data into memory before rendering. So if you want to make a map of a whole country, you will need a lot of RAM. Wheras with mapnik you load the map data into a database then render from that, so shouldn’t need as much memory.
I think Mapnik will probably be faster for making large maps.
Also, Mapnik probably makes nicer looking maps.