Which is the largest out of the violin viola cello and bass?

Truthfully I would say that bass is the best instrument. That is if you are looking for a challenge. It is a very large instrument with a large range of notes that can range from a low E (or B if you have a extension or five string bass) to a high G or D. If you want a beautiful instrument you can play cello or violin. But unless you are amazing at either of those instruments you are not going to get very far. There is much less competition if you play bass. This is a completely biased opinion. I hope your instrument searching goes well!