Personaly, i'm moored in Duquesa on the Costa Del Sol about 18 miles from Gibraltar
. It's a very friendly, quiet marina with helpfull staff and all the marina based bars, restaurants and shops are English
speaking. We're also far enough allong the coast to be away from the 'package holiday' scene so it's mainly older people and families.
If you want value for money
though, there is a brand new marina at La Linea, right next to Gibraltar
. It has floating pontoons and has to be the cheapest by far in this part of the world. You've also got the bonus of being a 10 min walk from Gibraltar itself for shopping
and Duty Free goods.