If you're leaning towards spears there's not much of a mandatory stat investment. The only spears that have remotely onerous stat requirements are the Dragonslayer Spear, the Silver Knight Spear, and the Pike, with 24/24, 16/22, and 24/10 Str/Dex requirements respectively. I'm not particularly inclined to regard any of the three as being worth the stat investment on their own.
Spears in general don't get very good stat scaling, so if I were putting together a character with the aim of using them I'd probably focus on either an Int or Faith build and take a spear down a non-scaling upgrade path like Fire, Lightning, or Chaos. That gets you the reach of the spear with decent damage and minimal stat investment, leaving more stat points for Vitality, Endurance, and your offensive stat of choice.
You'll be able to get your hands on a Spear that's been pre-upgraded to the Lightning upgrade path when you reach
, and that's generally regarded as the successor to the Drake Sword in terms of being a powerful weapon available relatively easily. It can comfortably take you to the end of the game if you upgrade it, and a fair number of people do just that on their first playthrough. You can also buy the Demon's Spear from Shiva in Blighttown if you're a member of the Forest Hunters Covenant. It does physical and electrical damage like the Lightning Spear but also has a unique R2 attack and is potentially available as soon as you reach the bottom of Blighttown.