As far as i am concerned i like the Poor Self Control qualities because they help shape the character's temper.
If my character has above 8 in composure i usually take Thrill Seeker considering it ends up having only a positive effect, but then it is role play, i also like vindictive and braggart (especially if i play a ganger or a sammy).
I always take the Consummate Professional quality, whatever i play, i always play a professional.
I like the allergy, but only mild for common while i take the 10 for uncommon types.
Addiction alcohol at mild level is an usual favorite of mine also.
I nearly always take SINer, usually at national level.
When i play a decker i always take curiosity killed the cat (i would go look at this file anyway, so i take the +2 to crack file as a bonus...)
When i play a ganger or sammy i often take impassive, i also had this one with a mage, but not a nice one.
I haven't tried the Bad Credit one from Complete Trog, but i gave it to my new troll adept face character (found the first effect during creation, no APDS rounds), don't know yet if the effect will be difficult.
I wonder also about the Force of Chaos one...