I have done both. The answer is that it depends on what the problem is your are trying to solve, and what the team who will be doing the work has skills in. GWT

I have done both. The answer is that it depends on what the problem is your are trying to solve, and what the team who will be doing the work has skills in. GWT uses the Java language and React uses Javascript so the two worlds are totally different. Recently I picked React, but seeing the recent improvements in GWT I realise that GWT has improved leaps and bounds in the last two years and does somne things better than react