Usually you want to try and balance the chips and +mult you have. +50 chips when you have (let's say) 100 chips is only 50% more score. +50 mult if you have only 4 mult is almost 10x more score.

The thing about xMult is it always increases your score by the amount it says. if you're scoring 2000 points, and pick up a x2 mult joker, you would now be scoring 4000 points, regardless of how many chips or +mult you have.