I've been biassed towards Atmel in recent years because of something that happened to me in '99:

Towards the end of a long project, we were upgrading old EEPROM based '51s on a board to FLASH 52's. I got about 3 standard Phillips parts - and could not make them run. I read the data sheet, swapped boards, swapped chips, read back the code to make sure the part had programmed .... nix. I even built a veroboard circuit with JUST a crystal, power and decoupling, and made a little test program that just drove the ports as a binary counter. Still nothing.

I also contacted Phillips, got some kind of obvious response, but no convincing explanation or suggestion.

This was the end of a long project, and I didn't have the time, so in desperation I bought some Atmel parts. The first one I tried worked perfectly ... as did the second ... and so on. So we bought 200 and used them. Since then I've tended to go for Atmel.

Now I really can't believe that Phillips make non-functional parts, but something silly was happening (or not happening). Any ideas what it might have been?