We have a saying here: "opinions are like arseholes - everyone's got one, and they often stink!" Which is what I thought would apply with your question, as marketing companies have spread a lot of crap on the Internet. But browsing through this thread I find a lot of good advice, so I thought I might throw my opinion in the mix:
Sodium Percarbonate (sometimes sold as "oxyper") is currently my favourite cleaner - it doesn't interfere with head, can be used no-rinse if left long enough or followed with enough acid steriliser, can shift just about anything with a bit of hot water and some time, is pretty economical and doesn't leave anything harmful to humans or yeast. Contrary to some marketing ****e, it is an effective sanitiser due to the oxygen released if it is left to soak. Unfortunately, you need enough solution to cover every surface and to leave it for some time, but it is still handy for stuff like kegs and stuff with lots of crevices that have to be soaked anyway.
Orthophosphoric acid-based sterilants (strictly speaking sanitisers, as they aren't very toxic to yeasts,) such as Star-San or any of the other phosphoric acid/sulfanic acid sanitisers of which some predate it. The great thing about this is that you usually just have to spray or shake it - the "surfactant"/foaming action of the sulfanic acid compound means enough will maintain enough contact with a reasonably clean surface for the requisite 2 minutes.
Boiling water. I continuously fill and boil the kettle during a brew to re-sterilise anything I have put down or dropped, then use the leftover water to fill the "airlock" if I am using one.
Some things I consider obsolete:
Bleach. Still recommended even by our Aussie Coopers, though I have not seen a bleach without scent and/or detergent here for years. It works, though it tends to persist and add flavours to your beer, and it kills everything.
Napi-San. Not sure if you have it here, but it is basically an expensive way to buy diluted sodium percarbonate, or oxygenated bleach, and I suspect contains things you wouldn't want in your beer.
Idophor and Peroxide-based sanitisers. They work - ask your mum or grandma if they were nurses in The War; Iodine and high levels of oxygen kill bad bacteria - the sanitising property of oxygen is used by oxyper, it's just that they are expensive and require a long contact time.