I have Fiskars and Olfa. In the 45mm with the ergonomic handle, the Olfa cuts way better IMO, but I still used the Fiskars 45mm for probably 15 years before bothering to buy the Olfa to replace it.
I know this is The Dark Side, but for cutting clothing fabric pattern pieces, I prefer using the smaller blades. I like both the 18mm and 28mm Olfa w/ straight handles.