deffinately hp.
Had one for about 6 years as the stoarge/browser system and it could do anything you asked it to, maybe not that quickly, but as it wasn't meant for gaming or making videos or editing or anything like that, it worked perfectly and was very stable. The motherboard went but even now i am still using fans, hard drive and card reader from it and all are still working fantastically.
As for dell, only experience i have had with them is my cousins desktop computer which i have spent so damn long fixing, never using, always fixing because it is one problem after another, it is a terrible system and if all are the same, then why are dell in business? Also, not that you need it, but if you are a user who doesn't know to much about computers they may aswell not give you support because theres is so shockingly poor