It's been a while since I mined at varrock mines, but it should take around 2-3 minutes per inventory of iron. With banking that's around 15 trips per hour. This will net you around 80k/hr.
Rune essence on the other hand takes around 2min trips with mining/banking. IF your F2p, then you'll only make around 45k/hr
If you're botting, I'd go with mining iron, it's good money and will raise your mining a lot faster, which will be useful in the future if you ever want to mine high level ores.