which is better
This flexing allows for axle articualtion over bumps and during body roll. Tubular LCAs w hard bushings (like poly) will also be a problem during articulation--they will cause suspension bind. This is why rod ends are used in many aftermarket LCAs. The rod ends allow the articualtion the solid LCAs take away. One end being a rod end should allow sufficient articulation, so a poly rod combo is a nice compromise to reduce the noise associated w rod ends, but loosing the flex/deflection.
But this is a vague question...my answer is assuming this is a street driven car, that needs to ride well and handle.
I also don't know what mods you have...but would put LCAs low on the priority list...IMHO.

