Hello 7rots51,
I have worked a lot with AB PLC's (MicroLogix, SLC500, PLC5 and ControlLogix) and just a few times with S7200 and S7300. I think there is no great diference in instruction sets, being the AB easier to master. The real diference is in the programing software. I think that the AB software is much better in terms of simplicity of use, monitoring and diagnostics.
Hope this helps
Best regards.
allen bradly software & configration tools are more far simple than siemens instead of that siemens software features is much more than ab so you can learn ab easily but to master siemens u will need to spend some time
I started with S7 Siemense and after 6 month I designed a 5 node profibus network with 6*64 I/O for a automatic refrig. production line.
So, Start with something that has configuration and base. I recomend you to work with siemense s300 or s400.