If you have H1, H3, H4, H7 or H11 then definitly get the new Osram Night Breakers. Not cheap for halogens but from whats been said they are meant to be really really bright for a halogen.
A standard halogen bulb does on average 1500 lumens, the measurement of light, depending on the fitting used. Then you get the HID Xenons now which produce between 2800 and 3500 lumens depending on the temperature of the bulb. Lower the temperature the higher the lumens, most OEM use lower temperatures because of this. Though the temperature changes the colour of the light, lowest for a HID is a white, then it goes to a blue tint, then finally goes to a purple tint at high temperatures. If you were to get a HID I would suggest the lowest temperature, due to the higher lumens.
But lately design of halogens have been improving, Osram and Philips have been making them more efficient. So they are the same wattage rating and fit directly into your car with zero modification. The best at the moment is the Osram Night Breaker I mentioned above, it is classed as a +90% bulb. This means it have 90% more lumens than a standard halogen, so this will give it a rough rating of 2850 lumens. Impressive really thinking it is just a halogen, plus a lot cheaper than a HID install. So if your car comes with the correct fitting for them I would strongly suggest them due to the performance to price ratio.
Maybe sidelights?
There no point in having amazing bulbs if they are only getting 10v or so.
