consumer grade LGA1151 motherboards are basically all limited to 16gb DIMM's. And memory is DDR = dual data rate == dual channel. So you always want two DIMM's installed. Will just one DIMM work, I'm not sure but it will definitely perform slower if it does than having two DIMM's based on how DDR works.
the H series vs the Z series, either can only use up to 16gb size DIMM's. The H series having only two DIMM slots maxes out at 32GB of RAM, whereas the Z series having four DIMM slots maxes out at 64gb RAM. So that will basically be your driving factor, if you don't need more than 32gb ram then H series would suffice. But also check out on the features included in the Z series which you may want.
for something like a high end Z390 motherboard, you will still see limited to maximum 64gb memory. But they have 4 dimm slots, if you can do 2x32gb ram and leave 2 dimms empty I don't know, check with manufacturer.
so... for 16gb DDR4 288-pin desktop memory dimms
32gb ram = $110
64gb ram = $220