Detect Invisibility:

Although other spellcasters can cast this spell as well, sometimes it is up to your Sorcerer to do the job. Invisible and partially invisible opponents cannot be targeted with spells which is very annoying, especially since you are primarily a spellcaster.

Resist Fear:

Although other spellcasters can cast this spell as well, follow the same logic as Detect Invisibility. Towards the end of the game, most of your party members will have low saving throws, but there will always exist a chance that they will fail their saving throws. Panicked party members are very annoying and dangerous, so this spell will ensure that such incidents will never occur.

Melf's Acid Arrow:

Dealing acid damage, this spell is nifty for finishing off Trolls. Lasting several rounds as well, it can also serve to disrupt enemy Mages' spellcasting. When your Sorcerer reaches level 20, the spell does a minimum damage of 14, average damage of 28, and maximum damage of 56. Not bad for a level 2 spell.

Mirror Image:

For those rare occasions when your Sorcerer is caught in melee. Although you will rarely use it, since your party tanks will usually distract the enemy for you, it can be handy when needed. This spell will also protect your Sorcerer from area of effect spells and projectile spells.

Ray of Enfeeblement:

If it works, it will make your day.

Web:

You are in a party, this will affect your party members as well. Not a party-friendly spell.

Blur:

Although the -3 to AC bonus sounds good, think about it, how often is your Sorcerer going to be engaged in melee combat? And if you are concerned about enemy archers, Stoneskin will always protect you. This spell better serves Fighter/Mages and Bards, your Sorcerer does not need it.

Agannazar's Scorcher:

Although the no saving throw is nice, the damage dealt becomes pathetic towards high level enemies, since the damage does not increase with levels.

Knock:

You are in a party, you should be having a Thief.

Invisibility:

You have Stealth, Invisibility Potions, Mass Invisibility, etc... ...

Glitterdust:

Although it offers the chance to blind the enemy as well, Detect Invisibility is easier to use and covers a much wider radius.

Vocalise:

Amulet of Power grants permanent Vocalise

Stinking Cloud:

You run the risk of knocking out your own men as well, not to mention that high level enemies have ridiculous saving throws against Death.