They both do a very poor job at that to be fair. Wikipedia will willingly allow editors to ignore actual facts in favor of a blogpost who wrote about the same event second or third-hand, and Snopes has no credibility at all, full stop.
I find your argument a bit cynical at best - this is a very black or white way of viewing two very large sites. Having read through Wikipedia decisions they are often open about the process, and the decisions can be very nuanced, they'll never be 100% successful, but they work extremely hard at trying to avoid bias and mistakes. I find Snopes to be a reasonable resource too, they present sourced facts as much as possible and whether or not I agree with all their conclusions I find the way they go about their research very compelling.