Actually I plunge a circular saw in and do the straight bits and then finish them with a hand saw. Never done one with a jigsaw as the last one I tried was pathetic, some Bosh muck I think. I also tried someone's battery jigsaw and that was even worse, a charged battery lasted about a foot.
If I want to rough out a hole I have a sabre saw that is pretty quick although, for me, its really a chain saw substitute.
Not that I do many sinks, I have done more hobs than sinks.
You can also do worktop joins with a circular saw that just don't work with jigsaws of any sort that I have seen. I guess when they are good enough to do joinery they will be good enough to buy.