I tried a "Big Mat" didn't like it, and got a Martelli. It's thicker than usual, so it feels different. Haven't had it long enough to make a judgment on how it will last.
On the Olfas - It just might depend on when the mat was made, and how long it was stored. I've got a couple of 12x18 that have been hanging around forever. One was kept at work since I preferred an Exacto knife for certain jobs rather than the paper cutter. Using it to cut paper for crafting this week, again using an Exacto, and it feels and behaves just fine.
I bought a rotating 12x12 mat about 3 or 4 years ago, it hasn't been used that much, yet it's dry and cracked. It could have been a bad batch, or else a change of materials in making the mats.