You can't compare the 737 to the 146. it depends on your requirements.
146: around 100 seats, short runway operation that the 737 can only dream of, only needs gpu if no apu, a little faster than turbo props and uses around 4 tons of fuel in 1 hour
737: 150+ seats, lot faster in cruise, needs gpu and air supply when no apu..uses around 6 tons an hour (I think?)
new european fuel tax's on the horizon???
if you need airframes and now, it is easier to get hold of 737's as they are more readily available.
Don't forget that 737 is in the jet category but the 146 is between turboprops and jets, cheaper crews......