If you're trying to put on mass bro, test is king of the road. Testosterone is the prime male androgen in the body, and as such still the best possible mass builder steroid we know of. Plus it's one of the cheapest steroids!
Yes, it has a high risk of side-effects because it readily converts to a more androgenic form (DHT) in androgen responsive tissues and forms estrogen quite easily. But these same things also provide it with its extreme anabolic tendencies. On the one hand estrogen increases growth hormone output, glucose utilization, improves immunity and upgrades the androgen receptor, while on the other hand a testosterone/DHT combination is extremely potent at activating the androgen receptor and eliciting major strength and size gains.
You honestly don't have to stack it with anything.
Then why choose anything else?
Because the other Class II steroids (dbol, anadrol, winny) promote protein synthesis by means other than bonding to the receptor sites. They promote growth by other means such as glycogen retention, etc.
Some do bond weakly becoming a weaker imitation of test.
But in contrast, none of them can compare to the explosiveness you'll get with a test ester.
But to get a grasp on the Steroid Classifications and what to and not to stack, read this:
http://www.anasci.org/vB/showthread.php?t=2210