Out of curiosity, what does notepad++ have that kate of other texteditors does not?
Looking at the features there does not seem to be anything special, but a lot of people seem to love it so there is clearly something special about it.
For me it's the TextFX menu and the MIME Tools plug in. They offer very easy access to lots of handy features like changing case (upper, lower, proper, sentence, invert), remove/swap/replace quotes ('/"), removing trailing spaces, non-printable characters, and blank lines (or just extra blank lines), base64/URL/HTML/ROT13/UU encoding/decoding, all kinds of decimal/hex/binary/octal/text conversions, add/remove escapes, etc.
Having so much there in just a couple clicks is very nice!
Looking at the features there does not seem to be anything special, but a lot of people seem to love it so there is clearly something special about it.