I haven't heard too much about either tyre, so most of this is what I've pieced together from stuff online, but from the reviews etc I've read it appears as if the Kumho Ecsta 712's are a better performance buy.
The
ZE326's are Falken's bottom-most spec passenger tyre, whereas the
Ecsta 712's are Kumho's best "street performance" tyre. The only tyre that Kumho has better are clubsport oriented.
I've never driven on a set of non-RT215 Falkens I've liked, and few people here like the Ziexs (although the ST115s have a somewhat positive reputation). I've been in a few Silvias and Skylines that have run Ziexs, and there was no grip. The damned things wouldn't die no matter what kind of sideways or smoking action we threw at them, and believe me it was easy to break traction since the things wouldn't stick to freshly-laid bitumen.
If these are Falken's "entry level" Ziexs......if they're anything like the ones I've ridden / driven on, God help the poor soul who tries to give it a squirt through the Nasho or a similar road.
And, this year, a WRX from Gosford finally beat Jim Richards all-conquering Porsche on a set of Kumhos (though probably the model up). I have a friend who races Formula Fords, and he knows a couple of racers at clubsport level that run Kumhos on their street and racing cars.
There is a guy using Falken Ziex ST115's in the V8 BRutes I noticed at the Eastern Creek Procar round. However, its only
a guy, and he gets the tyres for free. The driver approached Gary's Motorsport, who supply Dunlop tyres at motorsport events (and a lot of the field uses Dunlop Formula-R's) for a similar deal, but they told him to get stuffed since every other racer was paying for tyres.
Actually, the guys from Gary's Motorsport don't like RT215s. He thinks they're rubbish. The guys I met at Oran Park, who import Yokohama tyres, had grudging respect for the Dunlops and also thought the RT215s were rubbish.
It kind of reinforced my suspicion that the RT215s aren't all that good - they're just cheap, and because they are a semi-slick they're heaps better than any road tyre I've driven on, but compared to other semi-slicks they're like Falken Ziexs compared to AVS102s, S03s, or SP9000's.
Anyway, back on topic.....
If I had to choose, given that I don't know anyone who's had personal experience on either tyre, I'd bet on the Kumhos. One thing I've learnt from the cars I've been in is that, short of buying a renowned shithouse brand or retreads, you can't go wrong choosing the option that
isn't Falken Ziex.