There are few more frustrating and professionally embarrassing moments than standing in front of a group of people and having to say, " Wait there, the flash will be recycled in a moment or two..."
The two flashes you've mentioned are both perfectly fine, but I'm with other posters who point to the Canon 430ex.
But check Craigslist, Gumtree, eBay etc for a pre-owned 580ex or 580exII. There's nothing wrong with second hand flash gear. In 25 years of constant heavy use I've never had to send a speedlight type flash in for repair, except where my extreme carelessness has caused a breakage or meltdown while using a powerful external Quantum Turbo battery. Once I exploded the capacitors in an old Canon 540EZ when I got my first Turbo battery. I was working it hard on full power, loving the <1 second recycling on full power, ignored the warning burning smell and BANG! It was like a gunshot as the capacitors exploded against my forehead.
Either 580ex or 580exII will deliver faster recycling, more power plus the very compelling option of being able to hook up an external power source. This cannot be underestimated. Simple, get a 580.