what kind of beer do you like?
Darker brews (ales) are easiest...but just about anything other than the super light stuff (light lagers, pilsners) will be no problem.
Pre-hopped works well. I did a Coopers Stout plus 3lbs of Munton & Fison and the yeast that came with the can. Boiled up 2gal of water, dumped all ingredients in fermenter, added 3gal water, popped in yeast, bottled in 1 week, drank 3 weeks later, and it is absolutely incredible. Doesn't get much easier/idiot proof than that.