In the first place questions are:
1) Which kind of schematic
2) Which kind of FPGA ?
It is best to use manufacturer library to create a FPGA from schematic.
Why?
First of all you can simulate your design and see if it is working as you
expected, in short it will save you a lot of time. Guessing work is rarely a good thing..
Secondly by using primitives from specific supplier, it gives you a real advantage as they are most of the time optimized for the FPGA in question.
Disadvantage of using schematic instead of Verilog or VHDL is that it is not always 'portable' from ome FPGA vendor to the next.
Now I suppose that if you talk of FPGA imstead of CPLD it is because it is a rather large design, is it not ?
Cheers