Bitcoin don't have instant transaction. It can take up to 30 minutes even more to complete a transaction.

Best currency can also be questioned, for what purpose? it is the highest on the market?

I like Bitcoin, but would not say it's the best cryptocurrency out there. So many altcoins with so much better functionality.

So is this your opinion or do you have a source about the best currency and it's instant ?

Excuse me questioning your post, but I react to things that are not really true.