Very good question, I was beginning to swing towards 'last' as that person has by far the longest duration on there feet, but then saying that I could walk / drink Cider and come last without some much a sweat on so I've changed my mind and gone for 1st.
I would say Last if for them, just finishing the race wasn't the goal.
First may go through more pain but has the adrenaline flowing and the thrill of winning is amazing.
I have been first a few times. I have been last or two or three places from last too...
Definitely, it was more often harder to finish towards the end - except, again, when just finishing was the goal. Then, I would mind finishing after last :d