Your company is going against the flow then. Following the first successful prosecution for Corporate manslaughter, most employers are getting cash-takers back into company cars so they can control "fitness for purpose", maintenance and repairs, etc.

Because of this I'd suggest that you get something in writing that covers what happens if, a year down the line, the company decide to put you back in a company car and you still have 12-24 months finance to pay. That is a real risk for you and it needs to be addressed up front by way of a guarantee to meet any costs, or that you WON'T be taken out of the cash scheme for X months - and then take your finance to match that period.

You need to do the sums for yourself, taking account of the cost of tax disc, insurance, servicing, repairs, tyres, oil, etc. Offset these costs with the car allowance (net of tax and NI - ask if there is any salary sacrifice element), the Benefit In Kind you won't be paying any more, and any mileage payments you can expect to receive. ( If these are less than 40p/mile for 10,000 miles per annum, and 25p/mile for any above that, you can claim tax relief on the shortfall. If you are paid more, the surplus is taxable.)

Leasing doesn't work for an individual because you can't get the VAT back on the monthly rentals.

Any other method of funding is fine, but I'd lean towards a PCP deal like Ford Options. With these, you only pay the depreciation on the car, plus the interest on the money owed. The car makers often subsidise their finance for these, and offer deposit contributions etc.

Your anticipated mileage and return condition are important - they both have a direct bearing on the resale value used to calculate the depreciation so that is fair enough so long as they stick to BVRLA guidelines - and they are freely available ahead of handback time!