I'd personally try to approach this from another angle: what problem are you trying to solve?
I suppose you roughly have the choice of two or three loaders. Sort off. One for MBR partition schemes and one for GPT. And then there's one for UFS based installations and one for ZFS. And finally there's also Grub from the ports collection.
Oh, and I almost forgot about, I believe, boot0 which can be used as a boot menu (typing this from mind). Problem is that not every boot loader will be usable, depending on your environment.