My favorite faction ever since I started playing Mental Omega. Not because it's so good -in fact I always found it a bit underwhelming compared to raw firepower focused factions, but because I like the idea of psychic soldiers duking it out against conventional weapons. A bit X-man-esque, you know. Psychics not being a one in a million occurance but being numerous enough to form an army on their own has some serious implications. So much room for headcanon too. And fan fiction. And in general, epicness. I really hope that the end of the MO campaign will live up to the immense potential of the lore. Heck, the appearence of this many psychics could be the basis of the lore of a game on its own. Even though Yuri's Revenge had an ambivalent welcome back then, I'm certain now, that with Mental Omega, Yuri (the Epsilon Army) is the best thing that ever happened to the Red Alert series.
That being said, I find it that PsiCorps... doesn't nearly have enough psychics. A little bit better Adepts, sure. A monster tank that is made of Frankeinsteined brains of said Adepts. A few gimmicks here and there. And a heroine who got a very important role in the campaign but in the game... she is basically an overglorified grenadier. Point is, that the psychic aspect of PsiCorps is almost entirely represented by just a little more mind control. I think this wastes the huge potential that lies within its theme.
I really wish there was an Epsilon faction, PsiCorps or a completely new one, that would ephasise more on actually weaponizing psychics instead of using gimmicky technologies. A lot more glass cannon-ish and lot less subversive. I think psychics for Epsilon is like what Tiberium is for Nod - their very future in material form, yet somehow it doesn't really come through. Remember how cocky was Kane and Nod in general about their whole perceived "evolution" thing? How every aspect of Nod technology was influenced by Tiberium somehow? I wish it was similar with PsiCorps and psychics.