the best steroids that keep your gains after using are those that are slow and mild gainers. the deca's, primo's, EQ's, etc. fast gains = not keepable. generally the chances of keeping gains from orals are slim because they are such short cycles that you get quick results and that is it.
also the longer you have been working out and built a base, the better chance you have to keep it. it is so fucking true. i have been generally off of steroids for a year now and i still look like i lift, while other dudes i see come off gear and lose everything like balloons. it is because i have 20+ years of training under my belt, most of that was natural