Webpack is really easy to use and works very nicely with commonjs/nodejs style `module.exports` and `require` which is how I use it now. The place where it becomes incompatible is with the syntax that webpack adds to require statements. Stuff like `require("css!./file.css");` So you could use webpack to build things you once built with browserify, but if you start using `css!` you can't go back easily.
I prefer webpack just because how easy it is to use and how fast it is. It comes with its own watcher too, but I use gulp watch since I use gulp for building less, not the webpack less loader. I haven't wrapped my head around using `require` statements for less just yet.