My opinion go Balder Side sword, but thats based off the fact that I think buffed rapier is kinda tryhard Plus the Balder Swag Sword's r2 if you mixed leo on it buffed would be in-***-sane and ricard's r2 wouldn't get as much damage even though it's DPS would technically be higher.
The leo ring part was just a point out, not saying that it's only good with leo. It's r2 is face **** worthy regardless. Also 1 tip....... DOUBLE POKE
I'm personally leaning for the rapier,not for the damage(Although many people in PvP fear my CMD'd R2 combo just because it looks dangerous) but because of the looks B)
Balder side sword is a great weapon though and has a good range.
To the OP, why not spend an hour or so farming an additional slab in the lower levels of New Londo, during which time you'll also accumilate more than enough chunks, and then you won't need to choose one over the other.
Farming those slabs....... bane of my bloody life. I've spent 10 hours + (not at the same time) farming slabs with 410 discovery and NOTHIIIING, NADA, ZIP, a big fat ugly zero.
I've heard lots of you lucky people have found slabs there but not me.
If it helps, I have considerable experience farming Slabs, and will usually blag at least one within a twenty run-through cycle, with 10 Humanity and the Gold Serpent Ring.
Failing that venture into the Great Hollow, and farm the Crystal Lizards there, using the locate/quit/reload/destroy method!
yeah, been there done that too. all i ever get from them in the hollows is twinkling titanite and other goodies, but NEVER a T slab. i even followed Siegmeyer of Catarina's path and he didn't cough up one either, he should've jumped into the pit and fought but he didn't. then he gave me a ring instead of continuing on to ash lake for the completion of his story....... i'll trade a blue one if anyone has a T slab.
I love my BSS +15... absolutely <3 it!!! I've experimented with Ricard's and I do like it but the moveset of the BSS really speaks to my play-style. I really enjoy it for both PvE and PvP. I found that R2 (unbuffed) one shots a lot of enemies up until around NG+++. Ripost are pretty lethal. Regarding PvP, I haven't yet started invading; but, when I'm invaded it seems to me that most completely underestimate my BSS.