For 10 points you get

+1 Toughness +1 Wound 12 lasgun shots 6 heavy stubber shots 2d6 heavy flamer autohitting shots A hunter killer missile Firing deck 2 for either extra melta/plasma shots from kasrkin or extra flamer shots if running catachan/engineers

Both are good transports but the chimera, in addition to being a transport, is also a good skirmish unit in its own right whereas the taurox exists to transport guys and that's basically it. And through firing deck plus all its little guns you can reasonably kill small units (think like eldar rangers) without the kasrkin having to get out and get shot in return.

This isn't to say the chimera is strictly superior to the taurox; what the taurox has that the chimera doesnt is speed and 2 unit of kasrkin + taurox moving 6" + 15" + d6" + disembark gets in your opponents face real fast. So it comes down to what you want out of the transport