I have a 046 and I use a 28" bar. But I cut mostly douglas fir. Hardwoods would probably want a shorter bar. A 24" would be good.
Brand does make a huge difference. I've found the Sandvik-Windsor to both last longer and have a more durable replaceable sprocketnose tip. I'm not talking about the cheapo laminated bars-those are garbage! The Oregon bars are the softest and shortest lasting bars out there, and the Oregon Powermatch, the single rivet tip gets loose. I've had testing done on several brands of bars so these aren't just speculation. I've also cut quite a few million board feet of timber and have learned from my experiences.