I've slowly grown to favor leading commas in queries for two reasons:

1. It's easy to comment out a column for debugging or to explicitly show that there is a column that you are NOT using

2. I find commas at the end of the line or (worse, much, much worse!) in the middle hard to track down. I've had to look at too many things like:

SELECT a,b,c,REPLACE(REPLACE(d,'a','b'),'e','f') g,e,

f,h

My pet peeve is the deep nesting (> 1 levels) of subqueries where CTEs could be used instead.