There are many ways to approach this, as you have seen with good comments already.
An example would be that Ray Schuler offered at least 8 tapers as I recall, and probably more if you worked with him on it. The man was a genius and had at least 8 tapers available? Those were primarily carom billiard cues, but also pool. If you include all cue sports and styles of play it's a huge topic. And good cue makers tend to be pretty smart dudes. You can't always break down what they have done by the numbers like "measured deflection". It's downright black magic sometimes. Please let me keep believing that, don't burst my bubble.
Suffice it to say that most people that play pool prefer a "pro" taper, a shaft that remains the same diameter for a great length before tapering up larger, like 12 to 14 inches.
The most extreme type would be some attempts that are interesting but unsuccessful. Examples would be the old Flex-Craft cues with a straight non-tapered shaft into a handle, I have a couple versions in my collection. Over the years people often frowned on things like carbon fiber, fiberglass, and essentially anything other than wood, and especially anything without some kind of taper, but look at what is happening now with CF. It will not surprise me if at some point we see another serious attempt at something like what Flex-Craft did but with CF.
At the other end of extreme, the pure conical shaft, you will find a pool player that will stay with his pool cue while transitioning to billiards, but after a certain point they are likely to move to a billiards or carom conical taper.
In between those two extremes the possibilities of the variations of sigmoid and parabolic curves and the relative dimensions are endless.
Most of my cues are pool cues, only one snooker, and a few carom/billiard, and then several jump and masse cues. Most have some version of a pro taper. Even the billiard cues are not all fully conical. I have a billiard cue made by USBA National Champion Harry Simms, and it is not fully conical, nor is it a real pro taper. It's what he preferred I guess. Legend has it Harry ran 11 racks of 9 ball before he became a serious 3 cushion player, so I suspect he knew a thing or two about cues. I am fortunate to have had some exchange with someone who was close to him.
The lesson from that little story about Harry Simms makes think the discussion about tapers will be eternal, and there isn't a single correct answer to most questions on the matter.
I love to get four or five cues out and compare how they play. Just taking my Joss and all the shafts I have for it to compare is fun. I have two original Joss that play the same. Two Stroud that play the same, and one Scruggs that plays like neither of the other makers.
I think truly excellent players can often adapt to a wider variety of shaft types, so a banger like me might be more sensitive to it. Maybe a better player could describe the difference more intelligently though? Or maybe they just naturally adapt by their aptitude? Probably depends on the player.
How important is different taper for the player ?
I would say ask the individual player. Most will likely say it is very important, but after that any further discussion could vary wildly.
Then add diameter, tip choice, balance, etc. and we realize why this sport is so obsessed with that piece of equipment. It never ends and there is no answer...until the next great fad and the religion that follows it, LOL!