If you're considering using your own samples, be extra careful to read the "small print" on any drums VSTi that claims to support them.
There's two features that most drum vsti's have using their internal samples:
1. They use samples that are sampled at different velocities (i.e. multisamples), so you get a realistic timbre change depending on how hard you hit the drum.
2. They use several different multisamples of the above, and choose them either in a round-robin or random way. In other words they'll sample each drum say 2 or 3 times at each velocity, so if you play the same drum at the same velocity twice, you'll actually get two slightly different samples.
None of the drum vsti's I've seen support the above for IMPORTED samples. They just support one sample at one velocity setting. I've not done an extensive test of all the available drum vsti's though.
So if you are using samples of your own kit, going the soundfont (or sfz, or Kontakt) is actually not a bad idea.
But anyway, it's just something to bear in mind.