I wouldnt get the flavored ones... otherwise, my local bait stop carries the same worms (nightcrawlers and red wigglers), wax worms, etc. as my local Petsmart...
I'd get the red wigglers if available, unless you have bigger fish...
I feed by bichirs earthworms from the bait shop, they love' em, my oscars go crazy for them too. When I can find them, I get the smaller ones for my catfish.