Sebo_fan, I'm not that dialed in on all the vacuums out there, but I haven't seen an upright that filled from the bottom. What a mess that would be to remove the bag! I can't even imagine. How do you keep the dirt from spilling out?
My preference is for older Kenmore canisters. The only uprights I have had are a brand new Windsor Sensor S12 and an old pos Hoover U5133 something or the other, I call it a "U-Boat". Both of these fill the bag from the top. Do most uprights fill from the top or bottom?