I like size #3 and #4's because I tie 1/16 and 1/8th size jigs. I use Size 2's (most common size) for my 1/32 jig heads. It really depends on what size jig you tie most. I avoid rayon chenille because it looks cheap. Nylon is okay but I really prefer New Age chenille or Antron. Every thing associated with jig tying is personal preference IMHO.