Sorcerers are generally 'harder' to play than Mages. However, with a carefully thought out, pre-defined spell list, it is usually more powerful than a Mage. The thing about Sorcerers is, they can cast more spells than Mages, and in terms of raw firepower, they simply overwhelm the Mage.
This becomes more apparent in ToB, where you can have Lvl 10 spells. For Mages, you have to sarcrifice a Lvl 9 spell slot to cast a Lvl 10 spell. For Sorcerers, you need not to.
Six Dragon's Breaths... *drooool*... ...
Of course, Sorcerers do have disadvantages, the main one being the restricted spell list. However, as I mentioned earlier, if you take the time to choose your spells before you make your Sorcerer, you can end up with a really powerful spell caster. Still, Mages have Sorcerers beat, in terms of adaptability and variety. I will not deny that. However, my Sorcerer can handle most situations without the need to change spells and rest.
Think about it too, how many
different types of spells do you have per spell level? A Sorcerer can have five spells per level, which is more than enough for most vital spells.
Especially for Lvl 1 where I actually have the luxury to choose 'lousy' spells
Maybe for Lvl 6 and Lvl 7, you may have a hard time choosing, which brings us to the next question we magic-users must ask ourselves. How
often do you use that spell?
I won't say Sorcerers beat Mages in
every department, but really, they far from suck. With proper planning, they can easily be one of the best spell-casters in the game.
PS: Some choose Mages because they want to be able to earn Xp from reading scrolls.
Trust me, there's more than enough in the game to make this a moot point except for Dual-class characters.
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If not a Sorcerer, then a Paladin.
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Baldur's Gate Item Mart