You should go balanced if at all possible. Make sure your monitors are set for balanced operation though (refer to your manual) and that the source signal is also leaving balanced. If both ends are not balanced (signal wise) it really will not matter if you make the switch to balanced, in which case you may as well stay with what you have. If you do go balanced, I would go XLR. Not because it sounds better than TRS, but because the connection is more solid and in my opinion less prone to failure (due to outside negligence, not necessarily build quality).