You cook 1.1-1.2k an hour at rogues den, there's a fire literally next to the bank. You can trap the banker to stand right next to you while you cook by talking to him as he comes close. Then he's yours for good haha
And yeah firemaking is also super quick but it's just suuuuuper boring and repetitive
I also hear thieving is insane xp with monkey knockers or something like that?
Finally, with the release of runespan, people with 80+ RC claim of rates of 80k xp/hr and once you reach the 90's it reaches 100k xp/hr.
Personally, I suggest using powerbot/rarebot/simba.