In 2000, I went to work for GW and, while I had been playing Warhammer and Warmaster for a few years, 40K was relatively new to me. Despite my passing interest in the Necrons, my coworkers convinced me that I should collect Space Marines. At that time, the Necron army only had about 4 models, anyway.
I selected the Black Templars because they had a very striking black-and-white color scheme. I would be able to paint them quickly, and add some unique flourishes like purity seals and litanies. As I read more of the army's fiction, I fell in love with the idea of a crusade of what were essentially mini-chaplains. Their black-and-white scheme also reflected their world view of right and wrong (or in this case, loyalty or heresy) and an unflinching adherence to their doctrines.
My army, the Axalon Crusade, was constructed under the 3rd Edition Black Templar rules, which allowed the tactical squads to be equipped with a bolt pistol and chainsword, ideal for close combat. When the 2004 Space Marine codex was released, I experimented with fielding the Templars as "vanilla" Space Marines. Since the book allowed customization with chapter traits, I could construct an army with the flavor of the Black Templars, while trying out units and options that weren't available under the "proper" Templars codex, like Scout and Devastator squads.
The current Marine codex doesn't allow such shenanigans, and I wasn't very impressed with how the official Black Templars codex dictated army construction, so my army has mostly been on hiatus for the past few years. I have a handful of Scouts, Bikes, and Vindicator tanks in various stages of completion, but I'll probably hold off on building anything new until the next edition of 40K is released (which could be any day now.)
The Characters of Axalon Crusade
My Black Templars are nowhere near as fleshed out as my Vampire Counts, but I do still take the time to name the characters and vehicles.
Magnus Romero is the limited edition 25th anniversary Emperor's Champion model. He hasn't been customized at all.
The Marshal of the crusade, Samus Orion was constructed from a Space Marine Commander, with a simple head swap and the addition of a metal Black Templars shoulder pad. The banner, laurels, and storm shield came from the Empire Knightly Order kit, and the purity seals on the shield are from the Epic Reaver Titan.
Justinius Maximus uses the Chaplain #4 model, with a jump pack, plasma pistol arm and metal shoulder pad. The winged skull, representing the master-crafted pistol, was carefully sliced off the side of a bolt gun. That's Quovandius's back banner, from the 54mm Inquisitor range.
Among the in-progress models is my High Marshal in terminator armor. I'll likely make a few changes to his armament and banner pole when I finish him. But that will have to wait for now.