There are a number of third party tools for MAME to make system and software selection simpler. These tools are called "Frontends", and there are far too many to list conclusively here. Some are free, some are commercial-- caveat emptor. Some older frontends predate the merging of MAME and MESS and do not support the additional console, handheld, etc functionality that MAME inherited from MESS.
This following list is not an endorsement of any of these frontends by the MAME team, but simply showing a number of commonly used free frontends as a good starting point to begin from.
The MAME team will not provide support for issues with frontends. For support, we suggest contacting the frontend author or trying any of the popular MAME-friendly forums on the internet.