You can really go with any of the macro lenses from any manufacturer, they all give great quality shots with very little between them.
If you are going for a 150-180mm a flash and off shoe cord is advisable, anything around 100mm a flash is easier but you can adapt the onboard flash to work with it by making a diffuser setup for it, which I believe Alby done with his, perhaps he can advise on that.
I personally have the Canon 100mm for normal macro which is a lovely lens.