Generally speaking, Tableau prefers the data to be skinny, as opposed to wide. Option #2 would typically work better in Tableau. In your case, as long as the measure# represents the same metric (i.e., M1, M2, M3 all = Sales), option #2 is better. If each measure # should represent a different field (i.e., Profit, Sales, Discount, etc.), then shouldn't pivot the data and you would need to go with option #1.