People like to shit on IBM for good reason, but IBM is an enormous company so your mileage is going to extremely vary. I'm at IBM right now with good leadership and I'm working on some pretty awesome tech (not Watson). No one makes you wear a suit here... and my work-life balance is pretty wicked.
Amazon is def a better opportunity for advancement and what not, but most people leave Amazon after a couple years for the resume boost. It's more or less the same here, but with the caveat that you might get unlucky like the majority of what I've experienced with my other colleagues in my new hire network.
I would compare IBM Product Side to AWS. If your good at what you do (top college helps) IBM does offer higher base salary than Amazon. Amazon though generally is way higher because of RSU potential if you can survive past two years for the rest ... 40/40.
I did not choose IBM out of college and had a choice between Amazon and Oracle (didn’t get interviews at other top companies until after I accepted)... chose Oracle mainly due to location (social life, friends) and higher base even though the TC was identical minus the RSU vs Options aspect.
If your at Amazon you want to be in AWS, Labs / R&D, or Alexa. Most of my friends were miserable in other groups including the drone Avengers thing they were working on. The culture at Amazon is more cut throat where as Oracle and IBM are chill.
The group at IBM I am at now I wish was hiring when I was in college because of the exposure to the latest and greatest full stack tech. I am also on the client side so lower TC but the travel perks and learning opportunities are second to none. I am also betting Red Hat will help if we don’t fuck it up... I’m hoping they take over and fix our Cloud Platform and culture.
As others have said highly depends on team, research is better than most amazon teams. Wlb and remote working at IBM on average is significantly better than amazon. I encourage you to strongly consider this if peace of mind or family or stability is a large consideration to you. If absolute compensation is the only consideration than the answer would be different.