My 2 Cents/Pence/Eurocents
We run numerous notebooks including Toshiba, Dell and Apple at work.
The Toshibas have mostly been trouble free over the years, it's very rare to need to send one in for repair. The only black mark against them is we had a few Tecra A2s lose their screws, otherwise all the rest have been pretty solid. We had one that survived a deluge when water collected in the ceiling overhead caused the ceiling to collapse and flood the computer with water, a couple of days near a window in pieces and it worked flawlessly.
Apples, well we've had many G4 iBooks with discs getting stuck in the optical drive at least 15-20 in the last 12 months (fortunately the extended warranty covers it). We've also had a few MacBook Pros whose batteries have swollen up, and one or two Macbook Pros with charging issues.
The Dells we've only had for a year so far, but we haven't had any trouble with them yet.
We've also just got some HPs in so we'll see how they fare.
My personal favourites that I've used/supported over the years are Thinkpads, haven't come across one since it became Lenovo, but the ones they were making for IBM were solidly built, compact and built with mobility in mind (The lack of a Windows key was a bit of a pain though).
Also quite like the Toshiba Portege R500, a very nice piece of kit and prefer it much more than the MacBook Air we had on loan, can't stand the "chicklet" keyboard on the new model MacBooks.