depends on your situation.
I have a bad back and a heavy fanny pack tends to cause
me to lean forward more and adds weight to my tummy increasing
my back pain. HOwever , a back pack if too heavy is just as
bad.
I am woman and use a sling purse and it works great. It is
on my side and I keep it only filled with necessities...
you could experiment at the malls with the different styles.