Having had experience of quite a few in a short space of time, I'd say the following.
Panasonics are fast and work well in menus, they support more disk types including THEIR DVD-RAM format. However, they lack a number of features.
Philips, they have more features than you know what to do with, some are awesome, however and probably as a result of the above, interaction can be very slow at times particularly in menus. One of the biggest features over the Panasonic I have now and the Philips I had, is being able to do two things at once, watch and record etc. Also The Panasonic I have will not do instant rewind (like SKY +) the Philips did.
I spent another £100 on the Panasonic after crap customer care from Philips when it went wrong within days of purchasing. To me, that money was well wasted ....
Sorry, I know there are some Panasonic lovers above, there is no doubt they have quality, they just need more features for the money.
Bri