Which currency has the highest value globally today?

None.

This is a very relative answer. As far as the worth is concerned, the Kuwaiti Dinar is worth the most, at the time of this writing, the KWD’s relationship to the US Dollar is as under:

However, each and every currency in the world is government-issued, so it is subject to the ever-increasing money supply, and inflation, which makes the purchasing power of the currency decline every year.

So, strictly speaking, no currency is worth more than the other (on an individual basis) because of this, the value of it keeps declining.

Here is the declining power of the United States Dollar over the last 100 years, despite its dominance in the internal trade and monetary markets.

As all currencies in the world today are fiat, i.e. not backed by any gold or silver, but rather the full faith and credit of the government that issues it, no currency is worth the most as such. With respect to external commodities, like gold, silver, etc. The most worth one, being the Kuwaiti Dinar has already been highlighted.