I'd recommend good ol' Sears Craftsman. If you're looking for auto mechanic sets, stick with metric unless you are going to be restoring vintage US cars. Try their website. Many sets there not found in the stores.

Any type of tool purchase should depend on how it's going to be used. For a DIY'er the CHEAP Harbor freight stuff will work same as with Craftsman, Lowes or Home-Depot stuff. But for Professional use you will want to get the good stuff. Snap-On, Mac Matco Cornwell SK KD Tool AID OTC among others will hold up to daily use a lot longer. And you don't have to drive to the store you got it from daily or weekly or however long it takes to break the cheap stuff because with gas prices today it adds up. Remember this: YOU GET WHAT YOU PAY FOR applies in almost category of anything these days with so much CHINESE JUNK but prople will complain about quality but also want the Chinese prices on stuff. Qaulity is not expensive... IT'S PRICELESS. Your best bet is to buy stuff as needed and complete sets are not really needed, BUY WHAT IS NEEDED.

I have tools from many different sources. Alot depends on what price range ou arw looking at and quality. I have Craftman sets that for the price are nice tool with lifetime warranty. I also have tools from Harbor freight, with Harbor Freight I recomend going to one of their locations and checking out the tools they have reall y good tools at a very low price but they also have some that I would not buy. Mac, Matco and Snap On are 3 companies that have very Very good tools but at a VERY .....ah high Price. Now Mike (the Mac Vender that I deal with) has ordered me a lot of Sunnex tools. They are good quality and not as pricy as the Mac name brand.
Northen Tools have some great starter sets. They also have some sets with the tool box.