Both are very powerful sets.
Earth Control is, at least in my opinion, the best of the primaries for actual control, though this means it does little damage compared to others. Also, the amounts of -def is lovely.
Psi does good damage against most enemies (and little against certain ones, like mechanical ones; it's a tradeoff) and has some handy utility to boot.
Only thing i'de say about /Psi, is that it can feel like its a bit low on the damage output, and is a pretty slow starting set. And then you hit 38 
I have a Mind/Psi at L30 and it has felt noticeably weaker than almost anything else I've played (see my sig for some examples) with the exception of certain low level defender and controller combos I've tried - but apparently at 38 when you get Psychic Shockwave a /Psi dom turns into a god among men. Just know that the /Psi set is a very slow starter.
I actually took Mind/ as primary not just for concept but also for some extra damage cos I knew /Psi started slow, but it was still very slow and I felt like I was being "carried" by my friend's Plant/Thorn dom which I duo'd most of the 30 levels with. With Earth/ primary (a fantastic set - I have a new Earth/Fire dom that rocks... excuse the pun!) you'll have even less damage at the start, so expect Earth/Psi to take a long time to mature, but when it does you'll be mighty.
If you want a secondary that starts off with better damage than /Psi then any of them will do that, but /Fire is especially good, and /Elec and /Ice are great too (though I found the latter rather end-hungry at low level, like all Ice sets seem to be).
I had a question is it a good choice for a starting Dom player to use Earth/Psi ?
Any info is welcome