During development I mostly use the debugbar. This shows a lot of statistics about your app. For example the number of queries and which queries, the load time per page, which events are triggered and so on.
For production I use NewRelic most of the time. This is a very powerful tool, but pretty expensive if you don't use it often. You can find more information about it here: https://newrelic.com/php/laravel
There are a lot of tools that I can recommend, but what kind of monitoring are you looking for? Maybe a combination of some free packages are already good enough for you ;)