I went with the 80 Naxx Tier Helm, T3 shoulders, and some bluish pieces from several places (Ruthless Glad belt, Vengeful Glad legs, etc.). T3 is one of my favorite sets, so I'm glad it fits the Lightbringer Tabard.
I could probably fill in the other pieces with the DK Naxx gear lookalikes, but I'm fine with just the upper body matching.
I was going to suggest the Imperial Plate crafted set, but it looks like you're using that in the 3rd pic.
If anything, Imperial Plate is always a good default. The colors fit really well together. If you want scaled down shoulderpads (cause I know not everyone like the big, bulky ones), go for Heavy Mithril Shoulder
. They look a bit more like the Stormwind Guard shoulders.
I'm in love with the xmog ive set my mind to. Going for 9/9 challenge mod gold, light bringer tabard, and two Life and Death from naxx 25 off of gothik the harvester.
I use this with my Tank set, but I opted for Spine of the Thousand Cuts
. Took a LOT of farming, but it was easy gold and worth the time.