The local model for Belgium is I9505.
I9500/I9505 is supposed to support all 4G (LTE) bands and work globally. But some of them may be not activated in some regional models. That is the reason it is safe to buy local models.
Yes, most users probably prefer I9500, but only 20-30% S4 is I9500; almost all others are I9505.
For I9500, the CPU is better (for CPU intensive apps/games; for most users/apps, almost no differences) and the DAC (Wolfson) is better (arguable).