It is difficult to say which is the 'better' system. Internationally practice has tended towards North American 120/240 volt (with 440-600v or so for industrial loads) and European 230/400 volt. Each system has its good points and its weak points and everyone tends to be comfortable with the system they are used to. There imperatives that applied in the past (eg co-ordination with long distance open wire telephone circuits).
It is rather like two department stores in a city I know. One is 'up marhet' and the other one 'average market' (the history of this one is quite amazing). The then Managing Director of the up market store refused to be drawn on a comparison but merely stated that they were founded in entirely different circumstances. Discussion of voltage systems would be similar.
I doubt that there is any advantage going above 250/433 volts for general use. A higher frequency may be of some advantage for transformer design and because any induction or radiation effects might do less damage (indeed if this is significant in any case) to the body at say 80Hz.
I have previously wondered about an 'intermediate' voltage for lower density developments (with long services to residences) where underground reticulation is mandatory. A 11,000/230 volt transformer (fed by two phases - no HV neutral) at each house, cabling and fuses would be expensive, but a 1,000 volt scheme could be viable especially as it could use standard LV reticulation and service cable. However as 'off the shelf' transformers for this use would not have been available, I gave this away without too much further thought.