I've got a 4-year old Dyson DC03 vacuum cleaner. It's a slim, upright cleaner and is very lightweight. It requires no bag or filter changes and comes with a lifetime HEPA filter. Of particular note is its ability to clean up the tiniest of dust particles.
Normally I would just go out and buy the current equivalent model from Dyson but was wondering what else I should consider? I need a lightweight upright with all the usual tools and accessories on board, bagless, lifetime filters (washable if need be), the ability to vacuum up the tiniest of dust particles (this is very important) and excellent customer service.
I bought this particular Dyson as a display model and there were a few accessories missing. I called up Dyson and explained what was missing and had my credit card ready to buy the missing bits over the phone. They said they would send them free of charge and they arrived the next day! Hence, I am very, very impressed with Dyson service. It's also never gone wrong even though I am quite heavy-handed with it when cleaning my flat!
My budget is around £300 max.