Debateable. Voting without the free formation of opinion, and the right of political organization is worth nothing.
Humans automatically form opinions, and voting includes forming an opinion as to who to vote for.
Voting for the person to represent oneself simply does not require any organised political parties.
Without voting, there is no democracy, therefore voting is the most important.
Independence of executive, judiciary and legislature etc are nice to have,
and it would be difficult to run a middle to large size democracy without them.
Democracy in large states has the problem that the individual vote is very diluted.
The best solution to that is to have democracy at many levels as in India and
the USA where voters can also vote for state legislatures and governors etc.
The thing about China and Russia is it is all top down rather than bottom up.
Voting also requires candidates, and there is a problem here in that many
regimes e.g. Iran may decide who is permitted to stand or not to stand.
Needless to say US democrats are desperately trying to disqualify Trump.