If I'm reading the question correctly, it's something like the "which is heavier" problem. Work is work. If you use 200kJ to do a fast 5 mile ride one day and 200kJ to do a slower 10 mile ride the next, they obviously used the same amount of energy.

Now if you're talking kJ or kCal per minute, then faster always wins.

Regardless of pace, at least for me, 3.7 miles isn't even long enough to get my muscles warm-- so intervals would be out of the question. YMMV.