"Best fining" is not a possible question to answer, because different finings work in different ways and aren't comparable. Most finings work by ionic charges, and different hazes are charged differently and require different finings.
As has already been said, Whirfloc is more or less the same thing as Irish Moss, used the same way. I find Whirfloc to be slightly more effective, so I use that in every beer.
When I want super clear beer, I use something in the fermenter or in the cask as well. For lager (or hybrid) beers, I use gelatin, which takes out yeast like a charm, but also seems to do a good job on chill haze assuming the beer is already cold. If it's warm when you fine, most finings will not help your chill haze as all the haze causing particles are still in solution, has to be cold enough to bring them out of solution. For my cask ales, I prefer Isinglass, that works as well as gelatin, but is harder to use, isn't nearly as stable, but has the benefit of resettling if disturbed, which gelatin does not do, which is essential for when I need to move the cask to serving area.
Unfortunately, gelatin and Isinglass aren't suitable for vegetarians, let alone vegans. So if they're among your target drinkers, you'll want to avoid both. I have a number of vegetarian/vegan friends, and they simply have to avoid certain beers.
There are plenty of other finings you can use. Biofine is an option, as is Clarity Ferm/Brewer's Clarex, or PVPP. Each works differently, some tackling the same stuff, some tackling different stuff.
