There are some simple rules for leasing a car that usually if not always apply.
1: If you want a big additional spec then don't lease. Adding spec will kill the value of the deal.
2: If you want to do over 10K miles per year, it is likely going to be inefficient cost wise unless it's a really cheap car.
3: Be willing to accept the best deal over the perfect car and watch the end of quarter special offers for the best ones.
4: Be ready to move quick as the very best deals are usually 24 hour deals, the second best within a week of first advert.
5: If you want to buy the car at the end of the period (seems odd to do that) then lease will hardly ever offer that option.
It is not an alternative to buying if you want to build a car to your spec, do high miles or need to find the perfect model, colour and spec. If you want to build your dream car, buy it don't rent it.