If you're considering full squidger then I'd stick to 26, but for general use a front squidge 29 comes into its own.
Just remember its not all plain sailing - slower to accelerate, like-for-like the wheels are more flexi, greater surface are to clag with mud in poor conditions, heavier. They bring a lot of downsides but for general trail use on moderate conditions or better they can be a good grin.