I've been in IT since 2001.
I would very very strongly prefer to wear sandals, shorts, and a vneck tee.
I hate wearing long pants unless I am outside in the winter or some place that is cold.
I hate wearing anything with a collar.
I dislike shoes and socks unless there is snow, but for that, boots are better.
That said, I currently dress business casual (no tie thankfully), and for a long time I dressed in between business casual and formal (no suit, but was forced to wear a tie which sort of felt like being choked for 10 hours per day.)