Well the accepted advantage of AC is that with chunks of iron and copper you can transform it up and down in voltage at both ends.

Converting AC to DC, rectification is OK and has been since the invention of the diode, but inversion, i.e. chopping up  a DC to make an AC, has always been harder, although modern semiconductors are regularly raising the bar of what we might consider the highest voltage and maximum current, and so is getting easier.

Long gone are the rotating motor generator sets and attendant synchronisation problems of the last century. With inverters the link between frequency and load is broken, which makes interfacing with conventional rotating generation more exciting, as unless it is deliberately programmed in, phase shift cannot be used as a method of indicating or detecting overloads.


Against AC  the peak voltage is higher than the RMS by a factor of 1.4, and the losses associated with AC can be a problem - the polarisation of sea water for example makes high voltage lines undersea less practical. Displacement current in dielectrics make certain types of insulation failure more likely with AC.  So DC insulation and losses are better, but switching DC on or off, with no zero crossing to break the arc is not so simple at EHV, making circuit breakers more complex than the AC counterpart..


I'm sure there are other points and folk will add them.

Due to the capacitative impedance, for long distance transmissions such as subsea cables, HV dc has less losses so a cable from Southern Scotland across the Irish Sea to North Wales would be dc (England to France across the channel is short enough to be ac but would require synchronisation of the National Grid with the rest of Europe).