Mistwell said:
I suggest you reconsider Searing Ray then. The first level Orb spells from Complete Arcane are also worth considering.
I would also suggest that you consider scorching ray.... when you hit 7th level or so. Until you get two rays, flaming sphere is likely to be a better spell--particularly if you are an evoker and have spell focus evocation, etc.
Here are some points to consider:
1. Expected damage: Scorching ray does 4d6 assuming you hit. As a 4th level wizard, you're probably looking at 14 dex or so and +2 BAB. Assuming you don't have point blank or precise shot, you'll be looking at +4 to hit with your ranged touch attack and +0 to hit when firing into melee. Effectively, you'll be at -4 to hit when firing into melee and past cover (which will be pretty often if you make it your primary 2nd level offense). Assuming a typical touch AC of 11, you hit 70% of the time normally, 50% of the time when firing into melee, and 30% of the time when firing into melee and past cover. Expected damage: 9.8, 7, or 4.2 respectively. MAximized: 16.8, 12, and 7.2. (Note that, in the latter case, you're better off with magic missile and just when firing into melee, you get the same average damage from magic missile).
Flaming sphere does 2d6 damage assuming a failed save. At 4th level, I would expect your DC is somewhere around 16 or so with a 2nd level spell (16 int, spell focus, 2nd level spell or 18 int, no spell focus), but it could be better. Assuming your foes have between a +1 and +6 reflex save, you can expect between 4.9 and 3.15 damage/round--8.4, and 5.4 maximized. At that rate, you only need to use flaming sphere for two rounds before it deals as much damage as scorching ray--more in the suboptimal cases. If combat lasts 3 or 4 rounds, you're ahead with the sphere. And since, it's often easier to find optimal cases for the sphere than for scorching ray, (there's often little you can do about cover and melee combat that doesn't involve going around it and giving enemies a clean charge line toward you; on the other hand, targetting foes in medium or heavy armor is generally pretty easy unless everyone in the fight is a rogue (and in those cases, you're probably looking at a touch AC of 14 or so which will cut down the scorching ray damage too).
2. Endurance. At 4th level (and really, even at 6th level), a wizard can't expect to have enough spells to cast one every round and still make it through three combats a day unless he eschews preparatory and utility spells alltogether. Flaming sphere enables your wizard to contribute while using fewer spells.