I can't find anything I'd throw my cash at for £400. Rigol doesn't cut it IMHO.
The DS1054z has it's flaws but that is when compared with other modern entry-level scopes (like the HMO).
When compared with a 30 year old analog clunker, the DS1054z is still a vastly better scope in pretty much any regard aside from bandwidth and X/Y/Z operation (the Rigol, like most DSOs, doesn't have Z input).
And it's not that this is the only alternative. For example, the HP 54600 Series digital scopes are cheap these days, they are very reliable, and offer most of the advantages of a digital scope, including FFT (with the optional storage module).