If you are looking for a $30 headphone.. go with the Slim+..
There are some mixed reviews about the Surge's... I personally had to get a warranty replacement.
The Slim's are a great headphone.. I used them almost everyday.
The Slim+ is just a newer/updated version of the Slim's.. Don't think theirs any complaints but a lot of praises. One of coworkers has the Slim+ and he's been happy with them for the past 6-7 months.
If you can afford to shell out a lil more $, you may want to consider the Soundcore Spirit Pro,