I like the new Mazda6 and also the Mazda3, both nice cars. But for me it's a no brainer.
I would have preferred the TL but my wife liked the TSX better so we just got a brand new one last week; no navigation, I'm my own navigator and I never get lost

I really really like the car so far even more than I thought I would. Of course it only has a couple hundred miles on it. Both of us preferred the TSX over the Accord, but that's pretty nice too. We also still have an '89 Acura Legend since new which is my daily beater (so I don't have to wear out my '95 Supra turbo

) the Old Legend has over 105k miles, feels and acts like it will go another 100k at least without any problems.
Being a motorhead who enjoys driving on a road race course a few times a year and spirited driving most of the time, I'm already looking at how I can sneak a Comptech supercharger, lowering springs, low restriction exhaust, tweeked ECU, etc on the TSX without wifey noticing it - she never looks under the hood
As a related aside, a major national race team just switched their main race car from a Integra Type-R to the TSX since it has 2.4L vs the R's 2.0 and with some "minor" massaging, they think it will be much more competitive than the Integra ...even though they already kicked butt with the 'teg and are continuing to race it too from what I read. Based on a couple races already, it looks like their right about the TSX.
Fantasy aside, even if it stays all stock, this looks and feels like it will be a very enjoyable car to own.