I'd go with Crucial - I've had a very poor track record with OWC when it comes to RAM. The OWC RAM I've purchased and used for two different systems (a Beige G3 desktop and my current B/W) has needed to be replaced no less than five times. Either they sent me the incorrect RAM, the RAM they sent was faulty (which happened on two occasions, both were acknowledged by OWC as being faulty batches), or the RAM started to go bad within a year. I just received a brand new stick via RMA from OWC that still doesn't work in my B/W (instant lockup on boot) after spending a half-hour on the phone with OWC customer service. However, the folks at OWC tech support/customer service are really nice, and certainly they were helpful and friendly.
Hope this helps.