It is best not to use steroids just for fat loss, as they are not meant for this. In my opinion, for your objective the best thing would be Cardarine GW-501516 - it will give you good fat burning effects, will add a little lean mass, and will not cause side effects. Besides, thanks to its ability to greatly boost endurance, cardio and recovery, you will have a much easier time doing cardio training, which will also contribute to fat loss and abs creation to say so. On the other hand, steroids will cause a lot of side effects along the way, and will require more ancillaries and PCT. If your objective is as simple as you have mentioned, then there is no need to use steroids, as Cardarine (perhaps stacked with some other SARMs) will surely cover all your needs.