Craftsman has sets that never repeat themselves. Thats your best bet. You can get all sets and tool box for the price of a snap on toolbox. I didnt start buying snap on until I was sure(5 years) I was going be able to make all my investment back ten fold. Knipex pliers, snap on ratchets,Harbor freight pro impact sockets, matco air tools. Craftsman is not the best, but definately worth the price; I cant say that for everything I bought off a tool truck.
I not anywhere near a professional, but if I were in your shoes, I would get...
Craftsman sockets. Best bang for the buck.
Most people dont like Craftsman ratchets, but Ive been for the most part satisfied with mine. If youre using them to make a living, then I would recommend getting some nicer ones, but keeping the good ol craftsman.
Wright or Craftsman Wrenches. I own mostly craftsman RP wrenches, but the few Wright Ive picked up at the flea market are great. I would recommend the Wright over the C'man.
Channellock pliers (HD/lowes usually has good prices on them) and you can get used ones at the flea markets cheap too.
Craftsman Professional Screwdrivers. Better quality than regular craftsman, they have a solid build, and you can warranty them under the craftsman warranty. Slightly more expensive than standard craftsman, but in my opinion theyre worth the extra $$.
As far as other random tools go, Ive got
Bondhus hex keys (Made in USA, Got em because the C'man were chinese)
Craftsman pry bars (Can be bought cheap during craftsman club saver days)
Estwing hammers. (Cant really go wrong, but I have noticed more types made in Taiwan recently)
Other than that, I tend to stick to American made tools. Mostly for better quality, but also out of a sense of patriotism. Im sick of all the damn chink tools.