For the amulet the fury (again and dropping in cost just like bandos) is still generally considered the best option. For the cape you've been given the skillcape that has been trimmed, as well as the fire cape and OSRS gold the one-of-a-kind fire cape you get from giving up a fire cape while playing a minigame harder than fight caves. It's tough. It's extremely tough. It's a must to complete that search for that ring I mentioned earlier. It's not perfect however according to what I've heard, it's got great statistics.
Looking for the ability that earns the most is very vague, so you're likely to receive (and have received) some unrealistic answers. I'll go over some of the skills you could consider pursuing (in the manners in which they're taught by the majorityof people, so it's the most realistic - with the exception of Hunter jadinkos). They don't make money afaik but they're quite efficient.
I suggested red chinchompas as an option that could yield profits. Grenwalls are a different option, and more likely to make money however they're far more intensive in concentration and also much slower in exp/h (which is similar to the relationship between runite and Mining).
Fishing from 90-99 would make roughly 46 million dollars on Rocktails (I didn't include the cost for living mineral, but I'm guessing that can be offset by earnings made before reaching 90 Fishing) It would take between 180 and 190 hours (again excluding levels prior to 90, and assuming a 42k per hour of exp).
Mining from 1980-99 could make around 60M gold ore mined in the Living Rock Caverns and take approximately 220 hours (assuming an exp rate of 50k per hour). The Hunters from 80-99 could make around 35M from red chinchompas. The process would take about 150 hour (assuming 75k exp/h). Slayer or Runecrafting would certainly earn more money but it takes longer times to buy osrs fire cape get to 99. Ideally the best way is to go for 85 Dungeoneering. Then, just do frost dragons when you need cash, but you'll never be looking at getting any 99s quickly.