If you have an overwhelmingly positive Yelp profile, ranking it probably isn't such a bad idea. It may even be easier than ranking your own site.
As ibmethatswhoib said, there is potential for sabotage on Yelp and you can't control the content so it's not quite as safe of an option.
There are other factors as well - ranking your Yelp profile in the SERPs and ranking in Yelp's list of businesses in any give niche are two different things, and will give varying degrees of results. Though typically positive, if your profile is doing well.