What do you think are the most broken pieces of cyberware/bioware/nanoware in the SR3 books? In this case, "too good" means that it is too beneficial in some manner, whether by being gamebreaking or unprecedented (and for some reason undesirable) benefits, providing an effect that requires everyone to have it (or everyone engaging in some particular task, if you can defend the position that not everyone engaging in the task should need it), or renders an entire class of gear (cyber or non-cyber) worthless because of its existence by being strictly or almost strictly better than it.
The canonical example is the VCR, which provides the ability to vehicle-dodge at all, provides a raft of extra dice, and provides heft RN reductions for many vehicle-related tasks while providing mild TN reductions for most of the rest.
Another canonical example is the mnemonic enhancer, which provides the unprecedented effect of directly modifying karma costs.
Enhanced Articulation has been called Enhanced Artwinkulation for years, and has been for a reason. Just about every non-Awakened has this mod (except maybe the brain-in-a-box-style rigger), so I think it may be too much.
Others?
(Note: This thread is an offshoot of the SR3R -- Shadowrun Revised project. The project is being hosted elsewhere, to divorce concerns over copyright from Dumpshock, but topics like this I feel are perfectly fine on these boards, and may help garner more responses. If you prefer, you are more than welcome to register on the SR3R forum and post there; we would love to have more fresh bodies working on this project.)