When statistics do come out, some that you might want to consider are: Money earned per hour/minute, money it takes to buy enough of something to reach the next achievement, money spent (I'm not sure whether upgrades should be included in this), money earned for individual assets, ratio of money spent to either money earned per hour/minute and/or money earned in total (AKA bang for buck meter), and the time it will take for something to pay for itself (Reach a 1:1 ratio of money spent to money earned). Some of these would be best applied to individual assets, some to all of them combined, and some to both. Maybe you could apply some of these to upgrades themselves! Or even tell us how these stats will change if we buy something. Hope this helps!
 "AdVenture Capitalist"){kind=icon}
Great suggestions! Seriously - I'm making note of all of these.