Try them both out and decide for yourself. I prefer the P239, but you might like the G26 better. The P239 will be more slender(even with Hogue grips) and it eats up recoil a little better, but the G26 has greater magazine capacity. The P239 will also be more accurate. When I train with it I also shoot at 25yrds and I keep much tighter groups at those ranges with the P239 than with the G26. If you think the P239 grip isn't all that secure, a Hogue Wrap Around rubber grip makes a HUGE light and day difference and as far as I'm concerned.....a necessity.
One more thing to consider is the advantages to single stacked magazines. There is less friction as the rounds are being cycled upward since there isn't a funnel taper at the top. So, less spring pressure is needed to get the cartridges to the top, and the cartridges don't need to roll for feeding. Rolling increases friction and can be a problem in dusty environments. This is one reason why new Beretta M9 magazines being used in Iraq need to be kept so clean and why the USMC was favoring single stacks as part of the .45acp pistol project. Lastly, single stacks are less prone to jumble drops. Lets say that you chamber your pistol so that a round(or more) is depleted from the magazine. There is now a window of travel in the magazine and if you drop the pistol or the magazine the rounds can be jumbled in the magazine and become misaligned. A single stack is much less prone to losing alignment during a drop. So, there are some reliability advantages to consider with a good single stacked magazine. That being said, I still favor the double stacked P229 magazine for duty use and would not want a single stack. I do like the single stack better for off duty or CCW though.