Deca can be a great steroid for mass gains. Weight gain is good and stamina within a set goes up for me. It takes awhile to kick in, but I can always tell when it's working. I find that instead of failing on 20 reps of leg press, I'm able to grind of 4, 5, 6, even 7 more reps, pain free. And the pump after that set is amazing! Combine Deca with some long acting test and 6 wks of dbol and look out! Test/Deca/Dbol is the tried and true, meat and potatoes of mass gaining cycles. Sadly, deca is not what I would call a low side effect drug. As you've heard all over the net, "Deca dick" can be a reality. It's not going to happen to everyone and there are some ways to avoid it. You may have heard that running more test than deca will help to keep this side effect away. For many guys, this is true. 500mg test with 400mg deca is a standard dosing set up. For many guys, this works. Still for other guys, just adding deca in at any dose can cause some problems in the bedroom. Thats where caber comes in. .5mg 2x wk should be plenty to keep you F'ing like a porn star.

On another related note, Deca can shut you down hard and make PCT/recovery more difficult. I would suggest that anyone deciding to use it, also runs some HCG through the cycle as well. 250iu 2x wk, up to about 3 days before you start PCT will help ensure that you are able to regain natural function after you come off cycle. 

As for other options when looking to gain mass, EQ has a lot less side effects than Deca. I prefer EQ personally. Although the gains aren't quite as dramtic, less of what you gain is water retention. EQ is also awesome for endurance and keeps me powered up through my long training sessions. The key to watch on EQ is your RBC. You may need to donate a pint of blood 8 wks in. I know I'm getting close to needing blood work when I start to notice myself shorter on breath. As blood thickens, O2 moves at a slower rate. Either therapeutic phlebotomy or donate at the Red Cross