My vote....
Frankly, I hate that there's so much to choose from (in theory). Makes composing a cycle very hard if you haven't already "played the field" to see what works best FOR YOU.
D-bol gets my vote. If you aren't significatly gyno prone, you can use reasonable doses of it 20-30mg/day for a short period to jump-start a cycle or even use a low dose all cycle and get a benefit. Low enough dosage doesn't really require an anti-e if you're not prone to gyno. Great item to stack with an injectable you know works well for you. Esp. if you use the D-bol for fast results while the injectable builds up in your system.
I hear Sustonon is good, but I got a wierd reaction to it, so I didn't stay on it very long. Deca got me good results, but I hear you might as well limit to 600mg/week because the benefits per unit drop rapidly after 600mg so you're not "spending" your money wisely by taking larger dosages. Probably best to use in conjunction with another injectable if you want more than 600mg/week gives you. I'm no expert in that area.