A trailer would retain more of the "normal" motorcycle handling characteristics, but cargo trailers are generally rather smallish unless you had
one custom made. Even the smaller commercially available ones are almost 8 feet long when you include the drawbar length, too. I think
the sidecar (even if you got a basic cargo platform) would look cooler, but the bike will no longer handle like a unitrack vehicle then and
you'll have to relearn how to ride in that mode. You can look on ebay for a couple of motorcycle cargo trailer examples.
Still, I am hoping to hook up an airhead with a sidecar at some point.