There's really no "best" ladder as it will largely be determined by what you want the ladder for. One could argue that a "hang over the side" is best. Another could argue that removing the engine, installing a custom, full-beam platform/bracket assembly, adding larger trim tabs and some weight in the bow, reinstalling the engine on the new platform/bracket, and installing a slide-out 3-step ladder is best. Or anywhere in between.
There's plenty of pictures out there on the web of Spirits. It's easy enough to google that and see some examples.
But, a common option is to use an outboard swim platform with a single step. These are readily available at any local marine store and online. You might look to change the single step for an undermount 2 or 3 step slide out (or find one with that already). Or maybe a bracket-mount dive ladder would be another good option. Again, it comes down to what you want it for - more info from your end would help us help you.