If you can afford to work for Nationwide, a B737 rating and time on type is more valuable than anything at Link but at the end of the day, airline experience is airline experience.
By the sounds of it, Nationwide pay more than airlink at the moment - so no question about being able to afford to work there. Not only do you get airline experience at NTW you get Jet time over 30 tonnes too.
I would highly discourage joining link at the moment. Pilot's are not prostitutes - tongue in cheek!!