If you're looking for something slightly more mass-market but with the best writing experience I've seen out of such a pen, try the Pilot G-2 gel roller pen, pr

If you're looking for something slightly more mass-market but with the best writing experience I've seen out of such a pen, try the Pilot G-2 gel roller pen, preferably with a wider tip size (say, .7mm). Very smooth writing experience and good grips – the only downside is how much pen cartridges are very conspicuously less filled than they could be, and perhaps the lack of weight.