My experience differs on Osram vs Philips. Both seem to last well when matched with the right ballast that is working properly. Some of them are interchangeable between brands, with similar results. Overall, I have seen more consistent results from Osram, as Philips had some issues with some of the lamps supplied in some of the earlier DLP sets.
The key is getting the right lamp and that is not a trivial task sometimes. I would generally use what came out of the set. Regardless, make sure that it is really a Philips or Osram lamp and not a remanufacture or a cheap copy.
Current retail price on lamps for the Mits DLP RP sets are $100 and many replacements can be found for not much more than that for older models. Some are more, projector lamps are more.
When in doubt, use a reliable supplier or get the lamp from the TV manufacturer. It may cost more but you know what you have. Check the caps in the ballast and PS if either is suspect.