We used Slim at my last job. Seems a bit better than HAML in my opinion.
ERB just feels too “PHP” for me. 
ERB also has some weird quirks and it’s closed sourced… 
A long time ago I wrote two blog posts about ERB. You can read 'em here: https://ohm.sh/2013/11/07/failing-comments-in-erubis.html and https://ohm.sh/2013/11/15/even-more-failing-comments.html I never heard from the maintainer of ERB about my concerns.