Always buy the length rod that you are comfortable fishing with. I do a lot of plastic worm fishing and I am most comfortable fishing a 5'6" fast action rod, but that's just me. Just buy the rod that feels right for you. Also, it doesn't have to be the most expensive rod either. I use one of Bass Pro Shops $39.95 graphite rods and I can feel every thing that my worm drags across and sometimes it seems I can almost tell when Mr. Bass is even thinking about striking.