Is choosing places in the first row based on the worshippers' appearance and their pleasant smell considered a sin or arrogance?

The first is to be eager to be in the first row behind the Imam and close to him, even if there are none of those you prefer to stand beside. One should not abandon the best place close to the Imam and stand far away for a preferential reason. The natural inclination to stand beside a specific type of people is not arrogance, for arrogance is "rejecting the truth and despising people." As long as you do not despise anyone, there is no harm in that.