Mirana (fave/best) or Viper (great solo) mid, Tide/Rexxar forest (stunning ultimate). Won countless 2v2 battles with this, including a tournament.
Bane remains a prime choice of course, but kinda boring.
Omniknight is just extremely annoying.
ALWAYS go forest in 2v2.
Lately, more heroes have shown to be potentual forest heroes, some of which are used in normal games but doesn't do so well in 2v2. These include:
N'aix, Enigma, Troll (farm shitloads), Terrorblade and many others.
If you have the extra gold (I usually play with this), get HotD and dominate a creep. Get Quelling ASAP then, at least if you're melee. If you think you can manage without lifesteal, don't get HotD.
If you don't have the extra gold, your choice of heroes will be limited, and your farming will be slow...
That said, versus inexperienced (pub) players, I've won with Pit Lord and Ezalor, and even Vengeful and Techies.
Finally, you might want to get Diffusal, Linkens, Hood or BKB depending on the situation, namely Omniknight, nukers that gets dual Arcane Rings, stunner combos or harrasers.