[Vic55]

I currently own two of the cars in question and owned an M6 for 2 years back in 2007-2009. My short take:

If you only can get one car, its the M3- luxurious, performing, fast and a daily driver. Its the slowest but not by much vs the M6. Its that all around performer and I clearly like it more than the M6 it replaced.

The M6 is faster but its an 8/10ths car or more IMHO- I was always having to be in the 6k rpm range to push the car around. I weighs about 300-400 lbs more than the M3 and it felt much more piggish than the M3. The chassis feedback was not as positive and the handling characteristics left something to be desired. This is my opinion on the 6. I liked the looks when lowered with 20 inch wheels and the V10 sound is to die for especially with a modded exhaust. But it was the car I used the most and it didnt fit my needs or desires like the 3. The DCT clearly is the better tranny over the SMG IMO. Part of the reason I got the M3 was the DCT and how much I like it in the GTR.

The GTR is the best performer of the lot but its just not a daily driver for me. Its a big shell with blindspots and its too "look at me" for most. As for maintenance, its been relatively cheap for me. The 1k oil change is free, the next one was 150 bucks. No other maintenance is due yet but the 12k tranny fluid change will not be cheap- circa 600 dollars for me. The new software allows for unlimited launches under warranty so I dont worry about that. I honestly have never used LC as the car in "mash and go" format is incredible. For me its just too inconvenient for everyday driving, parking, and gas is ok. The GTR IMHO is a car that needs modding too. It reacts so well to the mods and its really not too expensive.

The GTR is the best bang for the buck performance wise as a 2nd or 3rd or 4th car but not as a DD. There are many that do use it as a DD and swear by it. If I did use it as a DD I would 100% not mod it as the warranty issues, although not prevalent with me, would cause to me want more piece of mind.