The simple answer is a Pickit3.
However it also depends if you are talking about a Genuine Microchip Pickit or a Far East cheap clone ?
Though Microchip no longer sell the Pk2, you can still buy, with guarantee, genuine Microchip Pk2 and Pk3 from the big dealers.
The far east suppliers have both at about 1/3 of microchips cost; I have a Pk3 clone, its worked for me so far.
The key difference between the Pk2 and Pk3 is that the Pk3 does program all the newer chips, however the Pk2 still can program a lot of the commonly used chips you find in the online projects.
One of the problems with the Pk3 is that for each family of Pic chips eg 16F , 24, 32, you have to reload the appropriate code into the Pk3 which can be a pain; also many of the good Utilities that came with the Pk2 were missing from the original Pk3, though they have made some software improvements.
The pk2 2.5 - thats just a Pk2 where the far east sellers have added on some accessories, like cable or programming socket