Paladins - fast at all levels, but after 200 (when you start to hunt grims) you can't get much more exp/h while botting. Need some skills at beginning.
Insane profits at chosens, ghastlies etc.

Knights - slow till level 50, then you can start botting yalahar/darashia dragons till 90 -> caimans till 120 -> sea serpents (around 200k/h) At level 180 you can go vengoth (400-450k/h if you are alone). You don't need much cash, 50/50 is enough at beginning (trainers will do rest). At level 300 you can make around 800k/h and insane profits at hive, banuta, deeplings.

Mage/Ed - really fast exp at all level ranks, but usually you will waste till level 200. Sometimes hard to bot (I was dying many times due lag/kick/comp lag etc - around 20 times from lvl 280 to 350, while on ek I died 3 times and took 300->390)
You don't need to train (you will get mlvl while hunting).
A lot of places to hunt. Example:
From 19 to 33 on Humans
33->50: earth elementals
50+: water elementals (best place ever)
100+: darashia dls
130+: fenrock dls

Nice profits at souleaters (around 180 lvl needed), lizard city (250+), quaras (idk, never botted) and if you are MS banuta -4 with gfbs (upto 150k/h gps on lvl 400+)

If you like manual it's fun to hunt (even lvl 50 at tombs with gfbs)