You can use a Plug tap (the common hardware-store type) for just about
anything. The chips clog it quickly so you need to remove and clean it
whenever it gets a little harder to turn. Maybe you have to break a few
to get the feel for them. I back off when I can see the flutes
twisting.

A Gun or Spiral Point tap pushes the chips forward into the hole so you
can turn it continuously in a through hole, but these chips are
difficult to pull out of a blind hole. If you have trouble getting a
plug tap to start cleanly (sometimes they just want to ream the hole)
try a gun tap for a few threads. Or replace the dull tap.

Use a Bottoming tap after the Plug tap to extend the threads nearer to
the bottom of a blind hole, if you can't drill deeper.

A Spiral Flute tap sends the chips out the top like a drill bit. I
understand that they are more brittle than straight flute taps but I
like them for aluminum.

Thread-forming or Roll taps squeeze the threads into the metal instead
of cutting it, so they are cleaner and can be run all the way into a
blind hole in one stroke. I haven't tried them myself and the one time
I got a job back where the shop had used them the threads weren't very
good.

The strongest? That may depend on the maker rather than the type. I
like Greenfield when the company is paying for them but my personal
stock is mostly cheapies or second-hand good ones that I have reground.

Simple & effective tap aligner:
http://www1.mscdirect.com/CGI/NNSRIT?PMAKA=06593016

Or you can drill shank-sized holes in a block to make your own tap
guide.

jw