Simply to bring this topic to the top I'll give an opinion. Buy 1/2" shafts, if available. Never buy sets. Never buy a bit without a specific purpose. Bits are expensive. An while routers are very useful, they are the most expensive tool in the shop. Like I said, bits are expensive. I have more invested in routers than I do the cabinet saw.
Often it is a case of buying a brand for a specific profile. Good brands are, but not limited to, Whiteside, CMT, Freud, Bosch and Amana. Generally speaking stay away from discount suppliers and related brands. It really depends on the particular use. HSS is perfectly good for some uses. Also, bits have a VERY short life if used. Not as many linear feet usage in any bit (carbide included) as might be thought. So don't look at bits as a lifetime, even project, investment.