I've had 4 sets of different tires on my my 08 G37S. Here is the best feedback I can provide to you IF you live in all-season climates:
Hankook Ventus Evo S1:
GREAT stopping and and handling. Very good hydroplaning resistance. Awful tread wear (about 12,500 milles @ 20% for a 240 rated tire).
Goodyear Eagle F1 GS-D3: Available at TireRack but would suggest finding new ones via eBay for the best deal. It's where I got mine. Perfect tire for this car at a great price for a full time summer tire. Amazing handling, stiff side wall, great hydroplaning resistance, and good tread wear. Tire wore evenly too which is great! I highly suggest this if you're doing a full time summer setup.
Blizzak LM-25's: Available at TireRack. Ok for a winter tire. I wouldn't say these are great for real deep snow or constant snow driving but they get the job done. They're good for areas that get only 2-3 big snow falls a year and you need to get home. Braking is ok but lacks in handling. Very quiet for when you're in the dry.
Dunlop Winter Sport M3's: TireRack as well. Amazing winter tire. I ran this tire in the back when I had a winter setup and the car hooked up with no issues regardless of snow depth. When playing around and drifting in the snow, these tires allowed me to have complete control over the car. I really like these and the price is fantastic as well. a LITTLE louder than Blizzak's but so little you probably couldn't tell. You'd have to really be listening.
Continental ExtremeContact DWS: TireRack. Ran me exactly $903.00 with shipping for the 245/275 setup. Tire so far is quiet and grippy. I've only had it in the dry but apparently from what everyone is saying, this all-season tire really shines in the wet. I was sick of switching my tires around so I wanted an all-season setup that proved to be equal across the board during all seasons and these were the few that fit the bill. They are a bit beefier, especially the rears. I have a small lip protector on my wheels now. They are also SLIGHTLY (about 5-7%) softer in the side wall than my Goodyear's but the difference is so small that it really isn't noticeable unless you're blazing a turn.
All in all, and to save you some time if you're considering these, I have not heard a single bad thing about this tire. From Civics to BMWs to G's, the general consensus about these tires have been the same: Amazing and worth every penny. I'll be sure to update in the Tires section once the first snow fall hits here
Hope this helps you and any others looking for tires. The more feedback on tires the better I see.