To bot rcing to 99 would take a lot of time but you could do it if you have decent summoning and the right equips...Theres a guide somewhere for that...
Smithing would be slow or fast. Depends on your money situation... Slow and profit...Smelt steel bars and make cannonballs. You'll only make money. But you could get gold smelting gloves and get 2x gold exp but you'll lose money that way if i am still up to date.
Fishing IMO doesn't get much respect if they fish easy stuff to get high levels... Fish to be rich not to have a 99... meh w.e not like prices are good anymore, but you might get where im coming from... Id fish lobs/monks to 80 then fish sharks. At 76 i got 90-130 an hour and at 86 i got like 150-200 an hour... Idk if you care too much about that though.
Woocutting is nice and easy. You can cut maples from 55 - (70-75) then cut yews at a nice rate with a d axe. Or get 68 and get 99 in like 3 weeks off of ivy.
Fletching, I think its a super gay cape just like firemaking and cooking, but ive actually considered it just for the 99, i wont even wear the gay capes when i got better lol. I wont even talk about them really lol. Just get them to be like yeah i got 8 99s when you only got 5 decent or good ones lol.
Mining, Seriously, fck money for this 99, just power mine...
Herblore - Expensive, fck this. But if you were going to try doing something cheap and fairly decent exp or go all out and do highest and most expensive pots. : )
Prayer - If you were rich, this is easier than 99 fletching lol. Bot gilded alter and youll get 100ks an hour. Very nice 99 to have too.
99 combat skills, id say get these first just so you can own anyone, fck skillers they get 1 hit
Summoning, ive never got it very high, so idk if its worth the millions but im sure it is.
Dungeoneering, woopty fckn doo. At least you got cool weapons.
Hunter... stupid high ban rate. why even risk it for 25-39m
Farming, just cause its a green cape and you farm herbs for it and get profit. But whatever, its a homo emote.
Agility, Gnome course -> Barb course -> Wildy course or Ape Atoll -> advanced courses. Sweet cape and no one wants to do it.
thieving, cool, no disrespect on it. high ban rate though
crafting, is nice but idk what is a popular or good way to get it, never really looked into it much. Bracelets, leathers and thats about it. from 10-60 you can flax for money lol.