Which Class to play on P99

[choklo]

I really enjoyed playing my necro alt on live 9 years ago. I only got to the low 30's before I quit though. I had a level 62 sk ogre too.
I have a lvl 7 chanter now on the back burner since starting my mage. The chanter was slow to level and a little dull and the mage was so much easier/faster to level.
When does the chanter start to get more interesting? Also, what is a "pocket" class? I've always wanted to try a chanter. When can you start to solo with them?