1) The 1-hand/offhand wizard. This is going to be a high DPS wizard, but they are going to run out of AP fast, especially if they have +attack speed items equipped. You're spending more AP per second, doing high DPS, but doing intermediate Damage/AP. A lot of wizard orbs (books) offer +maxAP and +AP regen as stats, as well as +damage. If you're playing this kind of wizard, it's likely that you're going to need at least 1 Signature spell that has runed AP regen attached. Each of the signature skills has 1 rune that regens AP, and this is no coincidence in my opinion. I don't feel it's safe for this type of build in higher difficulty levels to be waiting on AP to regen too often. They'll need to ACTIVELY regen AP.
2) The 1-hand/shield wizard. This is going to be the worst DPS wizard, but they're going to have strong defenses. AP will run out at about the same speed as wizard #1, but damage/AP will be measurably lower. However, damage taken will also be lower, leaving some room for additional casting of offensive rather than defensive spells more often.
3) The 2-hand wizard. This is going to be intermediate DPS, but they're going to have the slowest AP/sec spent, and the highest Damage/AP because they have the lowest attack speed. This is the efficient wizard. They're going to have to rely less on AP regen items and abilities, and might be able to have a vastly different AP stable spell loadout than wizard #1 or wizard #2. A good example here would be to use Arcane Orb as your main damage spell, then fill in with signatures when you run out of AP. This is in stark contrast to wizard #1 (and #2 to some extent) who must use Signature spells with regen attached to sustain themselves in intense situations.