The altminer is a more expensive investment. It can give you more profit with less power consumption provided that you find a suitable coin. On the other side, as already indicated, you could be left with nothing to mine. With the baikal there is less profit and more power consumption (roughly double the wattage of Z9 mini), but if nothing else you will have a selection of chose to mine.
http://cryptotomine.com/coin/algorithm-Quark