There are many factors to consider. External temperature, style of driving, the types of roads you travel on, traffic, hills.
Hybrids are ideal for short journeys, heavy traffic, urban and B roads and relatively flat terrain.
If you do a lot of motorway miles, drive longer journeys over a mix of terrain or have a heavy foot, you are better off with a diesel economy-wise.
That said, you then need to consider whether you are happy driving a diesel or whether you prefer a petrol/hybrid.
I drive up to 30k miles per year. Running costs are not one of my priorities and I like Lexus as a brand, its image and the design, comfort and reliability of its models. Having said this, if economy was my top priority, the latest generation diesel engines are excellent. And if anyone says they sound, vibrate and behave like tractors, this is an old fashioned view and you have not driven one of the latest diesel cars.
I can't really comment on pollution and emissions, because I don't know enough about it, but again diesel cars have moved on.
One final note: don't consider a diesel if you only do short journeys: you will not only ruin your engine and DPF but also pollute more than you would in a petrol, let alone a hybrid car, simply because a diesel engine takes much longer to reach its ideal operating temperature. A lot of people on the Isle of Wight and in the Channel Islands have learnt this at their expense.