I like my 09 Silverado LTZ. In terms of comfort, it's the nicest truck I've ever had, and I've had a lot of them in all my years as a builder. It's pure stock and plenty fast enough for me.

 

Chevy/GMC Duramax 2011 LML one of the best engines out there but little tuning available and owners now have to deal with filling up on exhaust fluid/urea. almost 400 HP stock

Chevy/GMC Duramax 07.5 & UP LMM
essentially the same as the LBZ but with the new body stile and extra emission junk. last year for EFI Live

Chevy/GMC Duramax 06-07 LBZ
another modest bump in HP. new injector design with virtually no failures. some will argue about the bad piston design but this may be more from fact that the rods are now stronger and the piston has become the week link. only in issue on higher HP tunes. overall voted best truck before EPA interferes

Chevy/GMC Duramax 04.5-05 LLY
the 04-04.5 still have the 5 speed allison. after that they went to the 6 speed. same basic injector design but changed the valve covers so the injectors could more easily be changed. tuned with 320 hp stock. these trucks seem to have an overheating issue from the restrictive intake design but replacing it should resolve it

Chevy/GMC Duramax 01-04 LB7
good running engine, easy to tune, tuns if aftermarket available. injector issues. injectors can be done for about $2K if you do it yourself. comes with 300 hp stock. best MPG stock


I like my LB7 but if i could afford it i would get an LMM, on a tighter budget i would go with the LBZ

 

I like my lb7. but the injector issue, $2000 + is hard to swallow.

 

It's all been said before, but I'll repeat it anyway:
2001-2004.5 LB7's - non-variable vane turbo, sound a little meaner with exhaust, lower stock power, 5 spd trans, and of course the 4k+ injector bill every 100k miles.
2004.5-2006 LLY's - no injector issues, 5spd trans, vvt, rumored to get the best mileage, had some overheating issues when towing.
2006-2007 LBZ's - No injector issues, 6spd trans, vvt, no issues. No DPF garbage, EGR pretty simple to get around.
2008-2010 LMM's - Same as LBZ, but with DPF. More money.
2011- LML's - More power, stronger blocks, no real issues, DPF, less aftermarket(not by much) than the older ones. More money.