hi there!

ahh, the eternal Sedu v/s Chi... well, how often do you use your flat iron? yes, i have indeed heard that Chi does not last long, specially if you use it often. but there still are people who swear by Chi for its effectiveness.
but if you want something that will last you like the great flat irons that your boyfriend gave you, then i'd advise Sedu

oh and i almost forgot, what kind of budget are you looking at?