Depends on if you want to pay or not.
Simba is good for being undetected. I haven't used Simba but I think it's only limited to certain bots. (as in some bots can't be made for it)
RiD(Robotz in Disguise) is great, but it's paid and takes over your mouse. It also only has around ten or so paid scripts, and two free ones(Power Mining and Construction)
RSBot/PowerBot is great. It's free. There is plenty (Over 1,000 I think) of scripts you can use. There's around 32 VIP($7.99/month) scripts and 31 premium(paid for) scripts.
I used EpicBot about two years ago. I never had problems with it, but supposedly it has viruses so I would stay away from it.
There's also a few threads in this sections about the different perks of each bot. It should be one of the stickied threads.
http://www.sythe.org/showthread.php?t=1449517
IMO iDungeon is the best bot, and I think everyone else will agree with me.
I think he was referring to bot not script, but I might be wrong.
Also, iDung still has it's flaws and it could have been written better. (I've heard it has 25k+ lines of code)
Scriptwise, I wouldn't really be sure what my favorite script is.
tehnoobSmelter(PowerBot script) is good for smithing. It could have a better paint(as in more stuff in it such as xptl etc) but it works perfectly fine.
iTBarbFisher(PowerBot script) is good for fishing. It gets stuck sometimes but it'll fix itself and still keeps a constant xp/h.
I haven't used the PowerBot one, but back when kMiner was in Nexus, it was a great bot. I'm guessing it still is.
Perfecticus has also began working on bots again, and has just released an Agility script (VIP only) in it's beta stage which should be premium soon. I'm sure that will be great.