With the Audis, it depends on how long you'll keep them.
The Lexus CT might not provide the performance and handling you're looking for.
I'd only suggest the ILX with the 2.4 and manual transmission.
The G37 is probably the sportiest, in S form, but not very fuel efficient. A good mix of performance and reliability for the price.
Compared to the G37, the IS might be a little more reliable and a little nicer, but less fun, a tighter rear seat, and more money.
The TSX and Verano won't perform like the Infiniti, but are a little nicer than an Honda or Mazda. The Buick has good front seats and is especially quiet, but a tight rear seat. It should also be the least expensive to buy, all else being equal. Overall cost of ownership with these should be lower than the other options--so it's a matter of whether they deliver the mix of comfort and performance you're looking for. A test drive should answer this.
I wish we had better reliability data on the Buick Regal. The 2011 hasn't been reliable. The 2012 might be better. We have nothing on the 2013 and up, as sales plummeted after the Verano was introduced.