I've had Furutech and WBT and WBT was by _far_ the better quality connector.
Having said that I've switched to inexpensive brand below for my latest speaker cables. I have 2-way monitors with external crossovers, so 3 cables per speaker. Very pleased with the results. The spring action makes them stay very tight even in larger openings when pushed upwards (long story but my crossover's connectors face straight down).