I haven't driven the latest M3, but I drove one of the E36 M3s and fell in love with it. I always regretted not buying one of those M3s. I seriously looked at the current M3, but they wouldn't let me test drive it.
The Lexus dealer was all too happy to let me drive the F, and I really liked it a lot. I think the BMW will give you a better ride/handling trade off, but in all other aspects, I like the F best. Especially the engine note. I followed a M3 coupe during BMW's Drive for the Cure (driving a 760LI, which was pretty darn cool in its own way) and wasn't that impressed with the sound of the M3. I like the deeper note of the F better.
What I really wanted was the C63. That has the most incredible exhaust note of the three (M3, IS-F and C63) IMHO. However, I would have to pre-order the car and would have no chance to test drive before buying. That was a deal breaker for me. I also wasn't keen on having to fill up the tank at least twice a week because the gas mileage was so poor and the tank wasn't big enough to give decent range.
Just to be clear, I don't regret my IS-F purchase at all. I like the car and think I made the best choice overall.
Just my two cents.
Jeff
08 Smoky Granite Mica IS-F