I recently got the PortaPros because they're, weirdly enough, cheaper than the KSC75s here ($20 for the PortaPros, $25 for the KSC75s). I gotta agree, everybody should grab a pair from this Koss family. They've become my favourite for work - they're not super isolating or anything, but everyone in this job has to wear headphones anyway so I'm not interfering with anyone with the small leakage I've got. Guys with cranked volume on their closed cans usually disturb me more than anything. I can wear them for hours without discomfort, they're breathable for summer use and fit well enough under winter hats when it's colder.
Yeah, I gushed about them a little while back, but I can still confidently say that the Porta Pros are the best investment I've made in this hobby. Of course I've got better gear, but the Kosses tick so many boxes at a low price that they're a real joy. I wish they'd been my first investment in this hobby and I certainly hope more of the new people give them a try before whatever bang-for-buck-hype-of-the-moment is doing the rounds. The Koss driver has truly stood the test of time.
I'm gonna get my sister a pair for her birthday. Hell, I'm probably gonna get them for lots of people's birthdays :).