I've been to Ibiza twice, the first time 5 years ago and then again a year later.
Obviously I have no idea how its changed but I stayed between San Antonio and the San Antonio Bay area, and got the best of both worlds.
The African guys did get a bit pushy trying to flog there stuff, but if you ignored them you never had a problem.
Back then the bars werent full of chavs, they all went to magaluf back then lol
To be honest I thought that San Antonio was the best place on the planet! Cheap drinks all night, great music, and very lively!
I was only 16 on my first visit with my parents, but they didnt mind me galevanting off all hours. If you know how to look after yourself out on the town in the UK you'll be fine in Ibiza. Just keep clear of any main roads while pissed :P
Of course this is all based on 4 year old intelligence so dunno what its like now! But looking at your profile, your 16-20 the perfect age for Ibiza
I dont know how lively u are but San An Bay is nice, and puts distance between you and the town so u dont hear it, but can easily just walk over to it.