The issue with RocketLauncher that I have found is that the media needs to be organised in such a way that is very incompatible with how LaunchBox is organised. RocketLauncher needs each game to have an individual directory with the media inside it, and it is VERY fussy about the naming being exactly the same as the rom, which Launchbox does not as it uses fuzzy matching.
This is definitely a holdover from its HyperSpin origins. HyperSpin relies very heavily on naming conventions and databases. This is where LaunchBox is leaps and bounds ahead of HyperSpin in my opinion. To me, Launchbox does for your ROM collection what iTunes does for music - it provides a gorgeous, intuitive interface that adapts to YOUR collection and saves you from having to mess with windows explorer.
That said, I still love HyperSpin and if it is ever resurrected from development hell, I hope they take a page from LaunchBox's book and have the frontend adapt to your collection rather than making you feel you have to adapt to their databases. There are so many talented artists that are still churning out boatloads of eye candy for HyperSpin - it would be so cool to see the frontend scrape all that material based on the games you drop in.
RocketLauncher was split from HyperSpin which was designed with arcade cabinets in mind. RocketLauncher's main objective is SEAMLESS game launching - taskbars, cursors, and anything else Windows are cardinal sins for RocketLauncher (afterall, you don't want to break the illusion of an arcade machine on steroids by pulling out a keyboard and mouse, right?). It does this extraordinarily well.
Full disclosure, I don't even have a custom cabinet - I'm an HTPC user. But for me, being able to sit on the couch and SEAMLESSLY control all the features of a boatload of emulators through Pause with nothing but a wireless gamepad is an awesome experience. This isn't even mentioning fade (which hides all the nasty Windows fussing as the emulator loads), bezels, keymapping, alternate emulator, and now global emulator shaders which are supposed to be integrated soon.
I love LaunchBox and its ease of use and ridiculously simple integration with RocketLauncher has made it my new official frontend. Plus, it's awesome to see it is being so actively developed and the passion shown by the developers. But to be honest, in my opinion, it has a ways to go before it supplants RocketLauncher with regards to emulator management.