First, from what you said, it seems that your home is no longer Yishui County, 30 kilometers away from Yishui. There is not much difference in distance and affection between living in Linyi and living in Yishui.
Second, from the perspective of development potential, Linyi undoubtedly has greater development potential than Yishui. Looking for a job, you must be easy to find in Yishui.
Third, the house is a place to live, so wherever you sleep every day, your life circle is also around the house. Of course, it is important to consider whether it is convenient for entertainment, medical care, education and shopping (this is very important). Yishui and Linyi can't compare with this.
Fourth, buying food is also an investment. Now house prices are rising every day. Even if the house is unoccupied, it may be profitable to sell it.
To sum up, there is no reason to buy a house in Yishui. So the answer is definitely to buy a house in Linyi.