I, too, have a preference for C/Cs because of their ease of cleaning - both the converter and the nib - and the ability to replace them easily as opposed to sending the pen out for repair. It's not a deal-breaker, I do have some Pelikans and TWSBIs and like them a lot but I also have an ultrasonic cleaner for thoroughly cleaning ink out of their nibs.
For me, they're also tidier to fill. I have micropipettes that I often use to fill converters. Keeps my fingers a little less inky