[Maria-discuss] 5.5.x vs 10.x

So, thinking of building a totally new server from scratch on a new vmWare host for playing around, and was curious of the differences. Is 5.5 still being maintained just because it is the last major stable version before 10.x? But then isn't 10.x the way forward? Is 10.x still considered a drop-in replacement for MySQL? Thanks, Charles