I'll throw my vote in on Haste, Fly, Polymorph Self/Other, Stoneskin, Teleport/TWE, Web, Magic Missile, Invisibility, and Spider Climb as well. Although, Invisibility is not as useful as it use to be (and that is a good thing). On the other hand they removed all of the 1st ed. restrictions that kept Polymorph Other balanced.
Dispel Magic - The most important spell in the game (Haste is #2).
It probably goes without saying but Detect Magic and Mage Hand.
Mage Armor - For the first few levels when Wizards are particularly weak, you can't live without it really.
Shield - Unlike Mage Armor, it's uses never really go away. Among other things, it becomes important at higher levels for stopping those quickened Magic Missiles that seem to fly around all the time.
Disintegrate - Essential high level spell of 1000 uses.
Anti-Magic Sheild - You may think that you are handicapping yourself, until the party has to face a wizard 5 levels higher than you are.
Wall of Force/Stone - Sometimes it is very important to be able to seal something off.
Protection from Elements - At high levels you can't live without it in most DM's campaigns.
Dimensional Anchor - At high levels you can't kill your main foes without it in most DM's campaigns.
Telekinisis - Very flexible spell that had to be toned down for 3 ed.
Globe of Invulnerability - At some point you will be high enough level that you frequently have to worry about combats with 4-6 7th level spellcasters. Not anymore.
Contingency - Get out of Death free card.
Forcecage - Very much overlooked spell. Get it.
Analyze Dweomer - Another high level campaign essential.
True Seeing - Ditto.
Wish - Get out of Death II, only 5000 x.p.
I know that is a long list, but you should basically want all or most of those. You could probably get by ok if that's all the spells you knew. Of course, it wouldn't hurt to fill in the chinks with any of the following close runners up: Charm Person, Endure Elements, Scry, Wail of the Banshee, Weird, Time Stop, Sleep, Tenser's Floating Disk, Unseen Servant, Dimension Door, Cone of Cold, Animate Dead, Rope Trick, Bull's Strength, Protection from Evil, Vampiric Touch, Mordenkainen's Magnificent Mansion, (Mass) Suggestion, Project Image, Protection from Arrows, Hold/Dominate Person.
I think probably the most overrated spell is Fireball. Not that it isn't a decent spell, but it doesn't deserve the respect it gets - especially now that it has been toned down in 3rd. ed. First, it maxes out at 10d6 damage, save for half. Secondly, most of the time that it seems useful, it is merely a shortcut for winning a battle that the party would have won handily anyway. Against opponents when it counts, its not that useful and may even be a wasted slot. Thirdly, evasion and improved evasion are not that uncommon abilities. Fourthly, resistance and even immunity to fire is probably one of the most common supernatural traits of monsters that PC's face. Fifthly, even if you empower it, it probably is no better than the higher level spell that you are replacing it with - and empower cost you a feat.
I can almost always find a 3rd level spell I'd rather have memorized.