I wanna know if Bitcoin is the best, the most secure, the speediest and the most precious currency right now, because there are many many currencies available and each offer some promises.
Is it logical to work with one or is it safe to somehow use several? Can anyone help me out?
you can not compare bitcoin, a cryptocurrency, with fiat the regular currency that everybody knows. in that comparison you will have a hard time.
but bitcoin is safe, good, fast, cheap and precious.
if you want to compare it with its counterparts also known as altcoins then bitcoin is the best. although you may find other coins that are faster or have other features but nothing comes without its downside. for example faster transactions means faster block generation and faster blockchain size growth and a ridiculous number of orphaned blocks.