You have to see which one suits your needs per say. I voted for the TL, The styling is very modern looking. Even though I love BMW's left and right, I always stare at a TL when I see one. I've driven a 3.5RL and it was pretty quick except for the fact I lost to a man. mx-6 in a straight line....started catching up around 110.
The IS 300 is well, nothing wrong with it, just doesn't give me a lasting impression of it like the TL does.
Either way your buying a Honda or Toyota, so, if looks are your deciding factor, then you should look at gas mileage, wear and tear parts and cost to repair/replace, storage capacity, safety and INSURANCE cost.
Hope it helps.