I ended up only really liking the Skirmisher.
The Templar is like a worse version of the Ranger with some mediocre psionic abilities thrown in. Some stuff, like their lightning ability, is nice, but still somewhat situational and requiring focus. I preferred just using the squad slot for a PsiOp which had much more utility. They're cool and I really want to like them, but I just can't really. My ranger beats them in nearly every way.
And to me, the Reaper feels like a glorified scout. They have some cool abilities, but they're almost all situational and it feels like nearly every single Reaper ability only has a single charge. Banish is single charge, they have two charges of Shadow, they only have one (or two if you buy that ability) Claymores, etc.. Remote Start and Banish are the only real abilities they have that contribute a notable amount to combat in my opinion, but Remote Start is extremely situational and Banish is single-charge. They're nice scouts, but I'd rather have someone who contributes to combat than a scout.
Whereas the Skirmisher is both good at combat and support. Their mobility is great, their control is great, so on and so forth. I gave mine a Superior Extended Mag and a Superior Auto Loader, which effectively eliminated their need to ever reload. It's mostly just the fact that pretty much every ability they have isn't turn-ending and they have lots of opportunities for extra Action Points.