I see the poll has ended, but I'd vote for the £5 million. My upper limit for imagining how much would be something like £100 million. Any more than that would be a bit silly. I'd be content with a nice house, some nice cars and not have to work but doss around all day.
lol
With £100 million, few decent investments, property and the like should be fine for life and not really have to worry, so long as one is sensible about it all.
One thing I have noticed, if I spend say £80 on something (legitimate say) it can seem a lot. But if I get £80 from something, it doesn't seem a lot. That make sense?