If you aren't too a young person – insurance premiums are daft for younger dirvers and if you have funds to put a decent deposit on a car, take the money. Taking a benfit in kind such as a company car and a fuel card could still push you into the higher tax bracket. If you can opt out of a fuel card, do it! The fuel card was what killed the company car for me. I calculated that I would have needed to do 14000 private miles a year to break even on what i'd have paid in tax for that card. My then employer had no alternative, so this forced the switch.
It also depends on how generous the company car on offer is versus the car allowance, but doing limited business mileage usually means it's well worth considering buying your own car as it won't devalue due the to starship mileage.
If you choose a company car, you are usually stuck with it for 3-4 years even if it's unreliable, uncomfortable, becomes unsuitable for your needs, ot you just get fed up with it.
Best thing I ever did was getting rid of my company car – it enabled me to buy a decent car with the money I would otherwise have paid in tax. All of a sudden, the IR were paying me money instead of me paying them.