Over the life of my Avy I've stayed with the Z71 shock setup and the newest ones I put on are still performing great.
Rears:
I replaced the rears with AC Delco 540-438 (GM Part 25871231). AC Delco is the actual OEM Z71 shocks (red color). When shopping for them, you may get a "does not fit" notice, this is because the part number for the 2007 model year has been replaced by a newer one. Keep an eye out on eBay, you can sometimes find a great deal on getting a set rather than buying each individually.
Fronts:
The fronts I purchased were AC Delco 139-105 (still OEM Z71 shocks - red color). They're a complete strut assembly (coil/shock). I've replaced just the shock the last couple of times, and then decided to make life easy and for the age, I'd just slap a new assembly in there. No fussing with a coil compressor. After searching around, it looks like AC Delco also has another "model" of that part which is a black shock, rather than the OEM red. I have no idea what the differences are.
It looks like front OEM Z71 coil & shock assemblies are getting harder to find. Snatch it up while you can... this was the only set I found on eBay: https://www.ebay.com/itm/139105-Pair-of-OEM-Front-Quick-Strut-Yukon-Tahoe-Suburban-Sierra-Silverado-07-13-/400997220286
Rear Axle Links
As much as new shocks improved the ride and handling, this past fall I also began replacing the rear axle links and I can not stress how much of a difference that made. It made the whole truck solid again! Literally felt like I drove it home new, and that was even before I replaced my tires!
So far I've replaced these rear items (both sides)
Stabilizer Links - GM# 15257472
Lower Control Arms - GM# 22868629
Upper Control Arms - GM# 15767252
Need to still do the single Lateral Arm - GM# 22863710
Hope this helps!