The beats solo are on-ear headphones. On ear headphones are smaller and easier to wear around the neck. Over the ear headphones like the m50x listed above can be more comfortable but will feel like wearing a neck brace around your neck.
If your looking for a similar on-ear type I would go with the sony MDR-v55. IMO it has a slight bass bias like the beats but not as dramatic. Overall I would say they're a better headphone.
Just for reference I do own a pair of beats studio executives. I got them because I'm pretty rough with my headphones and liked they're aluminum build. After a while I got tired of how they felt around my neck and the fact that they needed to be battery powered. I got the sony's as a replacement and they've held up well so far.