With the recent race/class changes, what is a good race for a mage and why? Thinking Aqua with psionics....

Merians make the best Aquas for obvious reasons. So far, haven't had any issues with Vesar being a merian psionic.

Merians are most definitely the best Aquas. You might be able to get away with something with a lower int and higher con if you intended to use only psionics, but then you'd be abandoning all hope of a damage kill and resigning only to Heartburst/Mindburst as your kill method, which I don't recommend.