I regret this decision immediately

This thing started when i obtained ornstein's soul.

I made the dragonslayer spear by "breaking" my 'lightning spear+2' to a 'spear+10' and i tried to use it, turns out its base stats are actually lower than my 'lightning spear+2', a lot heavier, and i cant even wield it properly because of the 24 DEX requirement. but upgrading it twice yields better results.

right now im making do with my claymore+10, my question is what path should i follow now?

earn 24 dex for the spear? (quite good at using spears now, because i had to use it throughout anor londo)
or claymore+15? (little training with greatswords but these are my weapons of choice or swords)

For me I would choose a claymore upgraded it to +15. Buffed makes this a serious weapon and can do serious damage with the right stats invested.

I would go for the +15. Ornsteins spear is good if you invest in dex and faith(lightning damage scales with faith) but as DSG said, claymore can be buffed

Dragonslayer Spear is good, but a Winged Spear +15 w/ Sunlight Blade has better damage, less weight, and a lower strength requirement.

If I had to choose between Dragonslayer Spear and Claymore, then I would choose Claymore. However, Dragonslayer Spear is really fun.

The Dragonslayer Spear also wears out quickly, so unless you have plenty of souls to invest in repairing it, I'd look for another option.

It does have a laser though. Vitally important characteristic, lasers.

It shoots LaSeRs?

That changes 28% of my decision, might try that spear on my next playthrough.

You have done the best thing. I always use the lightning spear to get a DSS. You should give it a go, it's such a classy weapon.