I would suggest typing "vacuum" in the search feature on mamapedia. Lots of questions about which one to purchase and great recommendations.
I vote Dyson Ball hands down. You will NEVER regret the purchase or money spent. You get what you pay for. We have the ball, lightweight version, and it does a great job keeping up with 3000sq ft, stairs, hardwood, carpet, etc.
No bags, no replacement parts & super easy to clean out & maintain. Not sure what Chantal is referring to but the filter and canister can both be submerged in water for cleaning. We wash our filter & canister (vinegar & H20--at least once a month) in the kitchen sink or with our garden hose in the summer and have had it for 5 years and not one problem. Highly recommend! Not to mention Macy's & Bed, Bath & Beyond have great coupons that can be applied to Dyson's for savings of $100 or so.