Some people like A-B, some LOVE IT! I learned on AB PLC2's and SLC100's. 8 years later, I am working for a LARGE tire manufacturer who had a lot of AB, and a lot of AutoMAX, and over 300 GE Fanuc, and a few of each of 20-30 small brands. Lots of experience with off brands here, I was scheduled for a GE school. Reluctantly I went. WOW. So much easier to learn and operate. Started using GE on all kinds of projects. A new tire machine was coming in with $22,000 in A-B hardware, I quickly did a comparison, and found out that for a little over $2,000, GE would do all that, and more, plus have a lot of analog comparitors AB didn't have, plus a second serial port that would be another $5K on AB. Personally, when I hear AB, I shout RUN. Let me say this, AB is very good equipment, it is pricy, and you can get a factory three-piece suit to come visit you, or if you aren't so lucky, a zero from a local supplier. GE and most other brands who are more cost effective usually have a distributor with an applications specialist in dockers, who will take you to lunch at Applebee's or Steak and Shake, give you litterature, and try to bail you out of programming troubles.
I love GE, and like Moeller "EASY" smart relays, and Entrtron Industries (Free Software, excellent tech support). Money saving tip...get a toolbox starter kit, you usually get the software free and some other goodies too!
Having worked as a contract engineer and consultant for many years... YOU ARE AS ONLY AS GOOD AS YOUR LAST PROJECT!
With fifteen years of A-B experience, and then working a couple of weeks on a GE project, a recruitor told me that they couldn't use me because I didn't have "CURRENT" Allen-Bradley experience. You can always use A-B skills, as far as older hardware, update as soon/as much as you can. Don't overlook PLC training here at PLCS.net.
Best Regards......casey