I'm no MySQl specialist, but on general principles I'd recommend the joined table method.

This may be a tad slower for the raw data fetch, but will be much easier to maintain in the long run, and will be extensible.

In general my feeling in these cases is that if you have a SQL database, then you should design a fully normalized database, and possibly denormalize afterwards if you realize that the number of joins become too unwieldy (which doesn't seem to be an issue here.)

Michael