I bought them in the following order Wii->PS3->360 and current play time is 360->PS3->Wii.
As i got the 360 last i have been buying up the exclusives i like the look of and have been ploughing through them, though on a normal day i would have to say the PS3 is the top of my list as so far it seems to have the best exclusives for me.
A plus for the 360 is the media centre functionallity, i have been using media centre exclusively for 4 years so this really is a great piece of kit. The UPNP is handy on the PS3 for people who havent had the ability before hand and the blueray is without equal. Cant really compare the Wii in this regard as it never prentended to be a home entertainment solution.
Comparing the networks for the 3, both PSN & Live are very good, is live £40 a year better than PSN? No, not really, and i really dislike the points system on both the 360 & Wii, pointless level of indirection which only serves to confuse the cost of everything. The shop on the Wii is dire, especially considering their hyperbole of thousands of VC games that failed to materialise.
As for cost, make no mistake if you want to get everything out of your console the Wii is the most expensive, i have controllers of all descriptions coming out of my ears. If you are on a budget then the 360 is gold, even the single player multiplat games alone make it a good investment. If you do have enough money to buy a Wii and 8+ controllers, do yourself a favour and buy a PS3 instead.
I bought the Wii early on as i saw the potential for innovation, and that is something that people seemed to get up mixed alot, potential does not automatically equal reality, after all this time owning it i have come to the conclusion that most developers for it are either cynical or lack any imagination - the fact that the top 4 Wii games making up almost 40% of total games sales speaks volumes about its lack of depth. I will however be keeping it, partially because of the amount i have invested in it already and more importantly im hoping much wider scope of developers will stop letting us down.