If to used as a custody meter you definitely want a coriollis for added accuracy. Otherwise you could use a dp type or rotameter. I'd not use a magmeter since it should only be organic and magmeters need some conductivity to measure correctly.
We are very short of information here.
What is the flow rate range?
Pipe diameter?
Pressure>~?
Temperature?
Expected accuracy?
Viscosity?
temperature range?
Is it flow rate, flow total, batch total, rest total?
Is there an available power supply?
VA meters are generally suitable for small diameter pipelines and low viscosity fluids (they are viscosity sensitive). The more you pay the better the range-ability (and accuracy - for high accuracy and wide range operation you need a precision machined float in a dual taper tube but you generally get flow rate, not total.
Magmeters require conductive fluids (though modern mag meters are able to function with very little conductivity). You get both rate and total.
Turbines are also viscosity sensitive so you need to choose a manufacturer that calibrates across a range of viscosities. They are accurate but limited range, give rate and total. A variety of electronic registers available.
PD meters are viscosity tolerant and, dependent on finance, you can have anywhere from 0.1% to 2% accurate, from 1/4" to 16" sizes, usually totalising but they start to get expensive if you need air eliminators and temperature compensators.
Corioplis meters, well yes, today coriolis meters are available low cost but usually comparatively high headloss though you get very good accuracy and wide range and you can have flow rate and total plus batch totals. Also available fiscal accuracy.
The magnetic flow meter would not be on my list for an oil based product.
jmw raises most of the issues. Biodiesel should be a very easy measurement. The line size and flow rate affects the technology selection. The first issue is the intent of the measurement. If you are looking at the flow within a process unit, orifice plates or newer technologies should work just fine. Custody transfer or batch loading tickets present different requirements.
