Fillet or weldment bead?
To be honest, you should only go to the trouble of adding weld beads or fillets if your model is to be used for:
a) A presentation or high quality render (nice, accurate welded joints are a small touch that adds a good impression for the trained eye)
b) A multi-user production office environment where the structural designer specifies the weld details in their model so a draftsman (or CAE analysis engineer) doesn't have to later.
For the most part, weld beads are a cosmetic addition that adds a fair bit of processing heft to your model with limited practical value in the long run. I wouldn't use fillets at all - lots of added geometry that you'd then have to turn off to get accurate 2D's. If you're trying to churn out production drawings for manufacture, you're better off just adding weld callouts and general notes to your 2D drawings - you only need to specify those once for a typical set of joints, as opposed to every welded joint in a structure (believe me when I say that detailing every welded joint in a large steel tower is a time-consuming NIGHTMARE).