Political parties are, obviously, very important in democratic systems. Most candidates will be selected by a party. But many systems make it easy for the party to control which specific members end up getting elected.
For example, in the UK's constituency-based first past the post system, every candidate needs to get a plurality in each seat (we casually say "majority" though they only need more votes than any other candidate which can be far from more than half the vote). But the majority of seats are "safe" and rarely change hands so whoever the party selects for those seats, no matter how poor a candidate, will, most likely, be elected. Congressional seats in the USA are similar, with decreasing numbers being genuinely competitive (and many being gerrymandered by both major parties to reduce their competitiveness). So, again, in effect, many representatives are chosen by the party not the voters.
But many proportional systems have similar amounts of party control. In mixed systems, like the Scottish Parliament or The German Bundestag, some seats are directly elected but the proportionality of the full body is ensured by selecting many extra representatives from regional or national lists. These additional members are usually filled in order from lists drawn up by the parties again reducing the ability of voters to choose which, specific, candidates from the party are elected.
The issue with the degree of party control in these systems is that this reduces the ability of voters to choose which party candidates represent them. This allows parties to guarantee the selection of many candidates who are not very good or who represent unpopular factions within a party. In the UK many MPs who are not very competent or diligent in their constituency work are safe as long as they are in a seat unlikely to change hands. In the USA many congressional candidates are selected by a party process that is dominated by highly activist members whose views are often far more radical than the general population, skewing the views away from the majority of the population (or even the majority of party supporters).
The ability of parties to control candidate lists in proportional systems or the makeup of candidates standing in "safe" seats has implications for candidate representativeness and quality. If members face no competition from the general electorate they can be far more polarised and less competent than if the electorate could choose among several members from the same party.
Are there any electoral systems that minimise the extent of safe seats and reduce the extent to which parties can control the majority of candidates who actually get elected?