Looking over the psychic spells, at least 3/4 of them target an enemy within 6 or 12 inches. This means that those spells are only really useful for melee-specialized units. Most of the time they'll just have no targets.
Because of that close-range limitation, it seems to me like the spells that target friendlies are way better.
Friendly spells always have a valid target, since you can cast them on yourself. No need to worry about the spell's range. No need to worry where you are.
You get multiple chances to cast a friendly spell, since you can cast them on turn 1 while waiting for contact with the enemy, and they'll last however long they need. That's a huge benefit in terms of reliability and predictability. Enemy-target spells are all or nothing on the turn you use them. You only get one chance.
A psychic unit with friendly-target spells can hide behind a corner while it buffs a nearby firing line, for minimal risk.
Unfortunately, some factions have only one friendly-targeted spell, while others have 3. I think this makes a pretty big disparity in strength between psychics.