Whichever one you feel most comfortable using. It's all up to personal preference.

PAT

sometimes it is more a matter of sound. for instance you may play A on the E string for a fatter sound. If you ever heard high and dry by radiohead you'll see what i mean. He starts (i believe) with f# on the E string, then g# on the A string followed by A on the same. He could get the same notes on the lower frets of the G and D string, but the sound would be a lot thinner.

Thanks Pat and Luis. That's good to know. It seems to me that you would have a little bit more control over the attack and decay when using the fret. What do you think in regards to that? Does that make sense?

certainly. sometimes a certain note will just sound better/sustain more in one position than another. It not only applies to the fifth fret over the open note option, sometimes you will have a "dead spot" somewhere, and you will need to play that note on another position. I have a dead C on the G string, a common thing on fenders, so I play the C on the D string.

And yes, you are very right: fretting gives you more control (ever heard the bass from "love me two times? The notes kinda "bounce" off each other, something that would be impossible to do with open strings)

hope it helped

I think it very well may help. Thanks

Generally, if your going to be playing around with the 6th 7th, etc frets, then move over to the 5th fret, and if your going to be playing around with the 1st 2nd and 3rd frests, then go open string.
Happy Bassin'!!!!

I would choose 5th fret for G and D, and open string for A and E.

It completely depends on your hand position when you're playing. Sometimes, the stretch to the fifth fret will be too much, and sometimes, it's just right. Also, kudos to Luis for mentioning the timbral effects...

For me,It would all depend on where my next note would be....
Sometimes I strike open A instead of fretting to grab my towel and wipe down sweat....like on sat nite.....bruuuuuutally hot !!!!!

There's no right or wrong here...A is A Dude !
Play what works for you...
:P
Peace Ed

I normally use the 5th fret cause i find it more difficlt to play short, sharp notes on the open string.