The two biggest computer sales giants are HP and Dell, both grabbing around
17 plus percent of the market so their prices are going to be similar,
although Dell's cookie-cutter approach will usually mean it is a little more
affordable for the bells and whistles.
I guess it comes down to service. Whatever you do I would go with a three
year extended service plan on whatever you buy. Also, as long as your
school/district/IT Dept. has a Dell Gold or Platinum account you should be
alright for parts and service.
I have no experience with HP service but have heard stories from both sides
of the fence, from really good to really bad. What would be really
interesting is to learn more about Lenovo, ASUS, etc. products, though I
suspect none would beat DELL on price...