For someone that works with metal, there will never be a "perfect set". Short of "one of everything", in which case the taps would be worth more than the house and all contents. For John Q. Homeowner, a simple "dime store" set for one time use can be found. Be it fractional or metric as appropriate, or both for someone serious. But for use a second time, a more serious approach must be taken.
There are a half dozen tap "configurations", each having a specific use. Then there is HSS(high speed steel) VS carbon steel.. Carbon steel will do (more or less) the job for non-ferrous metals and plastics. But for anything harder than brass, they will never hold up. I do a lot of tapping for small screws in plastic, brass, and aluminium. But with all the sizes of both metric and fractional, there are no carbon steel taps in my shop. From .75mm to 3/4 inch, my taps were mostly acquired a few at a time, as they are needed.
For a beginning metal worker, I personally would recommend a Sears (or the like) set. Two actually, one fractional and one metric. They will cover the more common sizes from Nr 4 through 1/2 inch and the equivilent for metric. Smaller and larger sizes usually are a little more costly and should be acquired as needed. Such sets will be of "plug" or medium taper. They will not include "starter" or "bottoming" tapers. They will not be "end all" sets, but will provide for basic threading as more is learned of the subject.
Personally, I very seldom use dies. Most such work is done on the lathe, possibly finished with a die. Just the way I do things. But as I buy taps, I look for a matching die as a pair. They are never (yet) used, but if I get into a situation where I need a "matched pair", it will be there. This applies particularly to non-standard threads. For a UniMat for example, the spindle is threaded M12X1. A "non-standard" thread. When I ordered the tap, I included a die. It trebled the cost and has never been used. But it's there if I ever need it.
For home shop use, the "standard" or "plug" taps will serve well. Some of the other designs are more for speed in production work. But for beginners, will prove far too costly for occasional use. Non-standard sizes should be on a "as needed" basis. For years, I did "instrument" work, before computers and fancy electronics. 1/4-40 was a common size for instrument feed screws. 1 rotation equated to 0.025 inch. Such is not so common today, but still shows up occasionally. As do other specialty threads. Such as 5/16-32, having calibration for 1/32 inch per rotation of a hollow shaft.
There is much to be said on such a subject. Some minor points covered above, many, many others implied. I, as a model builder, am not the most suitable person to be learning from. But, I have time to delve into some details where others don't.
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