Anything in the CS1 range. You will have to have a look at the processor line up to decide what you require.
You will have to replace the rack, CPU and power supply. With CX-Programmer, extract the program from the C200HS, change the processor type and CX-Programmer will re-alocate the I/O for you. If you have a commented Syswin program, CX-Programmer has a conversion feature that will retain all your comments. The latest version is V5.
All existing C200H(S) cards are compatible with the CS1 PLC so you will not have to change them.
You will need CX-Programmer to use the CS1.
By the way, the C200HS is still a current supported PLC.