Most of the time voters aren't really given a choice about the electoral system; it will be a decision that the politicians take for them.
The only time we've given voters a choice was in 2011, when there was a U.K.-wide referendum on moving to the additional vote system. From memory, I think the vote was about 65% to 70% against moving to it. In that instance, for the U.K. Westminster Parliament, people preferred the first past the post system and not enough people were in favour of changing it.