I was called. So, let's see
In terms of AP, Spy is 6.9 Megajoules iirc while Loid is 3.5–4.1 megajoules, AP is in Spy's favor, though it doesn't help that Loid has bullet- and stab proof vests to reduce the effectiveness of Spy's gun and knives. The same can't be said about Spy if Loid shoots him.
Speed is equal, so bleh, although Spy can increase his speed with some of his knives. Loid can probably handle this with analytical prediction, acrobatics, and his senses.
Spy's invisibility is countered by Loid's senses.
Their stealth mastery probably counters each other as they are both masters of disguises and espionage, with Loid having the advantage due to his senses once again.
There isn't anything written for Spy to say how good his hand-to-hand prowess is; Loid is decent as he has military training and could fend off armed combatants. And even if Spy is better, Loid knows when he is over his head and retreats, sets up traps, or uses the environment around him to gain the advantage.
For now, I put my vote for Twilight
