I like Zapan's best myself because they are of a simple design and follow in the footsteps of the older logos, giving them a facelift, bringing them up to the current times.

Also, the lightbulb is present, but not intrusive. Personally, IMO (And trust me, conitec probably has a marketing division that knows a ton more than myself), featuring lite-C in the logo is kind of detracting in a lot of cases. I find (In a lot of these logos, even though well done) that the Lite-C advertisement is too pronounced, pulling the attention away from the actual product.

Regards,
Ayrus