Henry said:
Because I do not see how a very tentative +2 CON vastly outweighs the benefits of flight, alertness, etc. - especially when a wizard is not high on hit points to begin with, and is quickly outstripped by the benefits of the other familiars. (Lucius is spot on with the other familiar's abilities being underutilized by a toad.)
Given the choice between an ability that makes one tougher and an ability that makes one more perceptive the powergaming choice is to become tougher. A wizard/sorcerer needs hit points; they typically don't to be good at reconoitering. Let the classes who actually have a talent for scouting do that.
The definition to me of an overpowered ability or feat is something that EVERYONE wants to take.
But EVERYONE isn't a powergamer. Someone might choose a familiar with a weak ability for reasons of personal taste. Players shouldn't have to choose the familiar they like over a familiar that offers the most puissant bonuses. All the familiars should offer abilities that whet the appetite.
And at any rate, "overpowered" should be defined by far less empirical methods than just looking at one's own group of gamers and deeming their choices to be representative of what *everyone* does. Some groups are more ahead of the munchkin curve than others
Honestly, how many people in your personal campaigns are picking toads as familiars? We've heard from two people so far, and I would be somewhat surprised to find that most of the people in their respective groups are doing the same.
Well, most folks in my group find 3e arcane spellcasters on the whole to be unappealing. 3e divine spellcasters have so darn many advantages over them (hit points, BAP, Fort save, weapon/armor proficiency, no arcane spell failure rate, learn all spells automatically, all-encompassing spell list, turn undead, domain powers, shapeshifiting, etc.), with not so much to tip the scales back up for the arcane casters. Familiars certainly don't cut it. IMHO, some folks have it backwards. Don't nerf the toad, but rather give some love to all of the other familiars.
But to answer your question, the handful of wizards and sorcerers that my group has seen over the last few years have for the most part passed on familiars altoghter. There's too much to lose when they die, and not so much to gain while they live. But the three that did have familiars picked the toad. Seemed like a no-brainer to them.