How would you compare the two? It would be great to hear the views of those who've had a chance to work with both YC and Dave McClure (assuming 500startups will reflect his style). Both seem passionately pro startups / entrepreneurs.
to differentiate a bit: 500 startups is a little more focused on design/ux issues, also platform distribution opportunities.
not that YC doesn't also cover some of these topics, but we might be a little more downstream from where YC starts working with companies, and we are also doing seed and some series A deals that are likely after YC gets involved.
Regardless we have a ton of respect for what YC does to help startups, and we aim to be complementary more than competitive... you might check with some of our companies that are both YC and 500 for more perspectives.
But in the end, it seems like the more choice you have as an entrepreneur for seed capital and more importantly, advice, the better it is...