If you like the Pilot G2 but are looking for an alternative then you've got to try the G-Knock (also seen as the GKnock). This pen is similar to the G2 in many ways, but is less common and featuers a different style grip.
This pen is fairly common in US office supply and stationery stores, under the BeGreen label. This isn't technically a subbrand, but it does tell is that the pen is made from 81.5% recycled content, which is nice to hear.
Pilot G-Knock basics
The G-Knock is your standard gel office pen, available in blue, black, and red. The most popular size is 0.7mm but 0.5mm is available, and 0.38mm can be found in specialty stores. The G-Knock accepts Pilot G2 refills so you can put in a 1.0mm Bold refill if you really want a smooth writing experience.
Pilot G-Knock review
If you know the G2 then you know the G-Knock, though the ergonomics on the G-Knock are a bit better. They write the same and have a similar click to them. They are both light, smooth, and fun to use. The G2 is the more popular of the two though, with the G-Knock being relatively rare