I rather dislike cool downs, especially if they're longer than a few seconds. Guild Wars 2 is all cool down, but you usually have a lot of options so you're rarely stuck with nothing to do. Magicka has no cool downs and has the best magic system in the world. I played a MUD (Project Bob!) that didn't have cooldowns exactly- Skills had an ideal recharge time, but if you used it again before that it would execute less effectively. Seemed like a good compromise.
I dislike mana pools, ESPECIALLY if they are slow to refill. If I have to sit around and wait after each fight, that's a major design flaw. Arcanum was kind of okay when you could advance time, but if you were inside you had to use consumables or actually wait 10 minutes for your fatigue to refill.
But the spells-per-day system is basically the worst magic system in the world, so I really hope they don't do that. I don't think anyone likes adventuring for 25 minutes and then sleeping for 8 hours. Or sitting on your best spells just in case a real fight starts.