I personally prefer Nork to Straken (But that's 'cos I have Cadians instead of Catachans; I also take Creed most games) but I think that Power Fists are generally useless on Guardsmen as the small increase in Strength isn't really worth the points (Unlike Company Commander upgrading to Creed). Go for the cooler-looking Power Weapon instead (Or take Creed). It's also cheaper.
The other option is to take Kell. After all, you get the model if you're going to buy Creed so you may as well use him, and he has both PF and PW! (Compensating for one of the few flaws of Creed)
I like Creed.