I recently picked up The James Brand's the Benton LTD for the limited edition Field Notes it ships with.

I love the look of the pen, but I found it a little unsatisfying to write with. It includes a black Schmidt P900 ballpoint ink cartridge but accepts any Parker-Type (G2) refill.

If you're looking to stick with ballpoint ink, the Schmidt easyFLOW 9000 gives a smoother, fuller writing experience while maintaining the versatility. It smears a bit easier than regular ballpoints before it dries (in a few seconds).

It seems G2-based gel refills are harder to come by. I ended up with the Schneider Gelion 39. It's more liquid-y than common gel refills, but writes smoothly. I like the matte, archival look versus the glossier ballpoint alternatives.