What are the best skis?

That is a pretty broad question.and it is a matter of opinion anyway.

The big variety of brands implies that there is no ''best'' brand, although skiers can be very supportive of their own skis. The three biggest selling brands in the world r Atomic, Salomon & Rossignol in that order. That does not mean they r the best, but they obviously have a lot of support. At the last Winter Olympics, Atomic hauled in the most medals, but that is because of who they sponsor! And of course professional racing is only one aspect of skiing.
The best skis r any u can buy for half price in a summer sale.

There r a multitude of skis made for different ability levels & types of skiing & conditions. The fatter the ski the better it is in powder, the longer it is, the harder it is to turn. Length also dictates speed to some extent. A shorter ski is easier to turn & better in the bumps. The shape of the ski dictates how aggressive u can turn it, & a beginning skier does not want a aggressive ski. There is also the flex of the ski, how easy does it bend, u do not want a stiff pair of skis in the bumps. l ski on Volkl AC4 is a good all mountain ski, & several manufactures make all mtn skis, they r all around good in numerous conditions.

There is no such thing. Some skiis r better than others for different purposes & different models & brands. There is also no longer any bad ski. l talked with an instructor on Sunday who was unhappy his top of the line race skiis, because they wee too stiff to teach with. My skiis for teaching r an all mountain model that was as soft as l could find in the shop.
One model may be better for one skier or another in different circumstances. The tune of the ski will also change how it performs. Keep them waxed & the edges sharp.