Oil may be a dearer initial outlay but will out last any gas boiler by a long way, you also won't be tied to any one supplier so can shop around for the best deal every time.
LPG is very dear to run central heating and with a tank rental tied to a gas supplier you are in their hands with price. Not a good position to be in
Electric boilers have come on in leaps and bounds in recent years but are still quite expensive to run, although, with not having much knowledge of these boilers I cannot really give a valid opinion. However, I would be interested to know how costly these are to run hooked up to PV Panels (or even if this could be done?)
Best advice would be to stick with oil, it is by far the most long term cost effective solution at the moment. And is the only fuel to come down in price, and is now on a par with natural gas. Yes, there is a possibility of price rises but with an over supply of oil due to USA fracking etc, it's certainly the safest bet and the one I would put my own money on.
Incidentally, your house smelling of oil does not mean your boiler is done for, it just means there is a leak, which could be down to a weeping joint, a cracked flexible oil line, or at worst a fuel pump. Not major problems, get someone to service it and give an honest appraisal of its condition. These things will last years if looked after properly.