Isolation also depends on your own listening volume - if you have someone with a tv on full blast and your headphones at absolute minimum volume, then you're going to hear them no matter what headphone you use. As soon as you have them say on 30-40% of a normal mp3 players output you probably won't notice any outside noise.
Heck I've been struggling to find a headphone that ticks all my boxes (sound isolation (both so I won't hear my coworkers as well as not disturb them), acceptable (Grado SR80 or better) sound quality, comfort, durability & the ability to quickly remove them (that last one ruled out IEM's for me)) for over a month and found it far from easy to find anything that ticks all the boxes...and I'm on a 250$ budget...ordered a KRK SN8400 earlier this week (200$ headphone here in switzerland), here's hoping...this may go some way explaining why people struggle to come up with adequate recommendations...