It has the capability to render at the N64's native resolution in case you don't like super sharp polygons with low-res textures.
Use this combination if you want best graphics or have a lower end PC and can't handle the General Use setup The default RSP plugin appears to be a slightly touched up port of vanilla Mupen64's RSP. There are many versions and forks of this plugin but generally it's less accurate than Glide64 and may have graphical glitches on some games, but it does well enough for most others and is quite fast.
Sadly, it will likely never see another update again.
The most recent version included with Project64 2.x (1.7.0.57-ver5) is somewhat buggy and has regressions, however, so the version included in Jabo's 1.6.1 patch is recommended instead for most cases, though the former can run in LLE mode, which can help with a few games. Very speedy, can potentially look the prettiest due to built-in AA and AF options, and is the only plugin with a widescreen hack.
Some users have also reported problems with BSODs, which apparently may be an issue with outdated Windows system files. Its RDB is somewhat outdated, and some games have issues with audio and timing regardless of plugin setup unless you mess around with timing settings.