Are you looking to clean and repair threads or cut new threads. For general maintenance and repairing a good quality tap and hex die set would work well. I have one of the large hex sets from Irwin/Hanson that I bought about 10 years ago. I also have a much older Vermont American set that is probably 25 years old that has been through me nearly my entire maintenance career that now resides at my home shop. Both the Irwin/Hanson and Vermont American are hex die sets in SAE, USS as well as Metric and made of high carbon steel. They have pretty much handled everything I've thrown at them with only a few broken that I have had to replace.
I also bought an import tap and round die set in carbon steel for actual thread cutting about 8 years ago from a yard sale of an old machinist guy and the set seems to work well despite being an import set. This is also a SAE, USS and Metric set with the larger round dies being adjustable.
About two years ago I purchased two extremely nice sets from my local Fastenal that they have made for them and marketed under their FMT-Standard label. One set is SAE and USS and the other set contains Metric. All have the fully adjustable round dies in all sizes and are made from HSS rather than carbon steel. These are truly high quality sets but they come with a hefty price tag.
Whatever you buy, don't buy cheap quality and buy depending on what your actual needs are, cutting new or repair as well as frequency of usage. I use my round die sets a lot and my hex sets somewhat less but I do quite a bit of machining in my home shop so more than merely general repair work.