[npost]

Horizontal. Though, vertical tends to have better short term results.

[callmeed]

Not only that, but vertical has a better chance of even making it past the short-term. With a vertical, it's much easier to find a pain point that needs to be solved, build it, and focus your marketing efforts.

[jacquesm]

The results of the poll seem to be bearing that out.

It would have been very surprising to see another outcome.