For Nexus you have to pay $15 a month or less, if you order for 2-3 months.
The free ibot is shit, its no good.
Nexus has a way better antiban and it also has a lot better payed scripts.
The Woodcutting script is a beast, as i used to use it, and i never, ever got banned.
Go to rscheata.net, there you can pay for Nexus or win it for free.
You can also check out HXS scripting team and there you will find the WC script which costs $2 a month or less.
Rsbot is way faster and free.
They are both good, but if i could get Nexus pro for free, i would pick it over RSBOT.