The Dungeon Master's Guide describes several player motivations (see page 8), in the form of archetypal player types. If you have players in your group that display any of these motivations, which of the pregenerated heroes of DL1 are most suitable for them?
Actors: Actor players enjoy thoroughly roleplaying their characters. Since the heroes of DL1 each have well-established personalities and motivations, any of them would be well-suited to serve as the PC of an actor player. For players unfamiliar with the novels, any of the heroes have enough built-in story hooks for an actor player to really make the character their own. On the other hand, for players who enjoy "playing the novels", Raistlin, Tasslehoff, Flint, and Sturm have particularly recognizable charcter traits that might lend themselves well to being taken on by an actor player.
Explorers: Explorer players want to experience new places, things, characters, and situations within the game world. Tasslehoff, with his insatiable curiosity and wanderlust, would be an ideal PC for an explorer player. Similarly, Riverwind, as a far-ranging wanderer, might also be a good option.
Instigators: Instigator players like to "make things happen" and may enjoy antagonizing NPCs, taking risks, or making deliberately bad decisions. Tasslehoff's impetuousness makes him a suitable PC for such a player, and Raistlin, with his contempt for authority figures and willingness to play devil's advocate, can also make a fine PC for an instigator player. Because she wields the Blue Crystal Staff -- the impetus for the action in "Dragons of Despair" -- Goldmoon can be a great PC choice for an instigator as well.
Power Gamers: Power gamer players enjoy the mechanical, rules-aspect parts of the game. As such, any of the heroes can be a good PC choice for a power gamer, but several of the heroes are closer to what might be considered "optimized" than others. Caramon, Flint, Raistlin, and Sturm might be the PCs most easily appreciated by a power gamer player. Conversely, Tanis is probably a poor choice for a power gamer player.
Slayers: Slayer players enjoy combat, particularly being effective at kicking monster-ass in combat. Caramon, Flint, Sturm, and Riverwind would all make good PC choices for a slayer player. For slayers particularly interested in the tactical aspects of combat, Tanis and Raistlin may be excellent choices.
Storytellers: Storyteller players most enjoy the narrative aspects of the game. Like actor players, storytellers can probably find something appealing in all of the heroes, but the heroes with the more complex motivations -- Tanis with his self-doubt and divided heart and blood, and Raistlin, with his complex fraternal relationship and precarious perch on the fence of morality -- will probably be of especial interest to storytellers.
Thinkers: Thinker players like to make plans and carefully consider decisions. Tanis, Raistlin, and Goldmoon, as the most cerebral and thoughtful of the heroes, are likely the best PC choices for thinker players. Tasslehoff and Caramon are probably poor choices for these players.
Watchers: Watcher players like being a part of the social event of the game, but prefer to limit their direct participation in the game's proceedings. Flint, with his grandfatherly, "along to mind the youngsters/one last adventure" mindset, Riverwind, with his reserved personality, and Raistlin, with his aloof bearing, may be good PC choices for watcher players. Tanis, as the de facto leader of the heroes, and Goldmoon, who bears the Blue Crystal Staff at the center of the plot of "Dragons of Despair", may be poor choices for watchers.