For me the perfect console would have the following features
Long life cycle - If I buy a console (especially a good one), I'd like it to be supported for a long time, possibly 8 years.
An abundance of high quality and diverse exclusive games - Exclusives should be well spaced out but frequent, cover a large range of genres like Puzzle, Platformer, FPS, Hack and Slash, Racers, RPG's and many more, and obviously be good.
Splitscreen - Make splitscreen a viable option with lots of games that support it.
Balance between physical and digital media - Customers should have the option to choose either digital or physical media, no option should be compromised like physical copies taking up space and lacking manuals, while digital copies take too long to download.
Customisable library and UI - Players should be able to sort their library however they want, and change the view style. E.g. From a list to a grid, and be able to change the size of the icons.
Good controller - Comfortable to hold, makes use of as many fingers as possible, suits many genres and has a long battery life. Have more than one controller to give people options.
Online store - Easy and quick to navigate interface, lots of deals and a wishlist function to tell you when games are on sale.
Storage space - HDD with plenty of storage, discs don't need to be installed and save data/patches and be installed on portable memory cards for portability.
Image and video capture - Images can be captured by using a dedicated button, videos can capture the last 15 mins of gameplay or the player can press start and it will record until the player stops it.
Music - Have multiple ways to put music on the console, and allow it to be played during games.
Portability - Easy enough to move around and fit in tight spaces, durable, and multiple outputs
Speed - Quick loading times, be able to get into a game almost instantly.
Stability - Not break