In terms of reliability, going with any stroker kit will actually lower it once you're pushing high power levels through them. I would bet a 2.5L would be more reliable since it's generally not bored out like a stroker kit is.
Personally, I would want to go with the cosworth because I believe they add displacement only by adding stroke, and not boring the cylinders. That, and well it's Cosworth. They're awesome.
Also, Crawford tends to use a lot of the stock STi parts in their blocks and replace what they need to. They're also a bit less expensive. The crawford block will generally have the stock bearings, crank, and maybe a few other items, whereas the cosworth will have cosworth bearings, their billet crank, etc.