If you were going to choose one product only, then I would recommend IGF-2. It will provide you with lean muscle gains whilst allowing you to stay relatively lean (andd even lose some fat). Strength gains, muscle hardness, and enhanced recovery (minimal or complete elimination of DOMS), and great sleep are also benefits of IGF-2.
If you wanted to go the hormonal route, as Jason suggested there is always The ONE (but if you've just had along hiatus from training, then you probably shouldn't jump straight into such products).