I've got a 3 strand barb wire fence thats almost 20 years old. For the most part it keeps the cows out of a few acres and I plant my plots in there. The visual temptaion should be there and every so often I'll find that one has crawled in. I'd bet 4 strands should be better but never got that far.

Personally I'd avoid electric. Don't want the deer any spookier than they already are....

Jeff