Personally I would stay away from taps made specifically for hand tapping. They are often made of carbon steel which won't last as long, and don't self clear the chips so the tap has to be reversed every 1/2 turn or so to break the chip. A spiral point machine tap would be my choice for through holes. With this style tap the chips are forced forward through the hole. They don't have to be backed up to break the chip and the flutes don't get clogged up.
For blind holes I would use spiral flute taps. They push the chip back up the hole so it doesn't collect at the bottom. They make it far easier to tap to within 1 thread of the bottom of the drilled hole.
There are lots of good names available on eBay. I only buy new taps from industrial suppliers like Zeitlin Industrial Supply and H&H Industrial Supply among others. Quality names I've purchased over the last 3 years include Hertel, Widia, Regal, YG1, OSG, Union Butterfield, Greenfield, Cleveland, Triumph, Morse, Eclipse, Jarvis, Pratt & Whitney, Chicago Latrobe. I most often buy them by the package rather than individually. I find this method decreases the unit cost enough to make it worth while.
A GH3 is .0015 over for instance , every number= .0005.
