The Mokka is built on the same platform as the Vauxhall Viva and Chevrolet Spark, so space is never going to be their best asset.
Haven't owned a FR-V, but we did look at them as a replacement for our other car, a large petrol MPV. They're a bit of an oddity, quite wide because of the 3x3 seating - the only other similar thing is the Fiat Multipla. The petrol autos aren't too bad on fuel, mid-30s I believe, but the road tax is a bit heavy at £290. They seem to be as well put together as any other Honda, but even the last ones are getting on for 10 years old now.
We ended up having a whirl with a more conventional large diesel estate that does 60mpg, costs £30 a year to tax, 160bhp and goes like the clappers, but I miss the high up driving position and ease of access of the old car.