Not exactly fair, all these devices have their strengths and weaknesses.
For instance the Venue 8 Pro has access to the largest ecosystem (Windows applications) including a vast army of open source programs but on the other hand doesn't have quite the range of tablet optimized programs as iOS or Android.
Nexus 7 and iPad Mini retina have great displays and colour quality (although iPad Air does better than Mini for the purist). Venue not so great.
The old iPad Mini and iPad 2 look worst value of the bunch now, couple of years time when all the cool iStore apps require 64bit A7 these will look very sad indeed.
Tho I must admit this resale value we so often hear about is something of a mystery to me, never encountered anyone in real life from this apparently bottomless pit of people prepared to buy generations old technology for a modest discount over the up to date models.