Well, you'll have to research that one yourself to see what fits you best, i.e. your goals.
Be aware that you'll find dozens of people who will happily tell you "Use___________, it's awesome!" But why trust someone who may know less than you? Almost any product has it's own unique side effects, and typically it works out to be that the stronger the product, the stronger the side effects.
if you have no fear of hair loss, gyno, acne, liver problems, etc..... then go ahead and use the strongest thing you can find. Worried at all? take it slow, and research, research, research.
Example: It seems a lot of people jumped on the Superdrol bandwagon from day one.... for months, all you heard was pretty darn good stuff about it. Now? I am hearing more and more regrets........
Personally, I care more about my health than muscle size. Vyotech 17-HD and Ergopharm 6-OXO are about as extreme as I go. But on that note, any minute now someone will say that even those are bad choices.
if you have specific questions about products, feel free to message me.... I have researched quite a few of them for clients and can make some good points.
Overall Message: Make your own decisions.... it's your body. Beware of people who flat out tell you to do something.... chances are, they didn't do any research.