Topeak rack has a nice attachment system for their baskets, panniers, trunks etc. to attach to their racks. The basket just slides on to the rack and locks in. It's great if you want to occasionally use a basked but don't want the hassle of figuring out how to bungee it or use zip ties every time.
That said, on my old bike the rack was close enough to the seat that putting a basket on left very little clearance between it and the seat. I didn't like it. My current bike has a longer wheel base and the rack sits further back from the seat, so it's probably ok but I don't have the topeak rack to fit my basket any more.