Recommended PS1 plugins

Firstly, stop using ePSXe and use PCSX-R.

GPU

3D: PEOPS OpenGL 1.78 (Comes with PCSX-R, has an anti-jitter funtion "GTE accuracy", and allows driver forced AA)
OpenGL 2.9 (If you run into problems with 1.78, want to use filters. Or want to set a custom rendering resolution for within the fullscreen box, aka window resolution.)
2D: gpuBladeSoft 1.41 (Very accurate, but renders everything on CPU so can be very demanding at high resolutions. Fairly buggy past native as well, with texture alignment and whatnot.)

LilyPad latest SVN (under Input APIs set Keyboard API to Raw Input)
LilyPad-SCP (Comes with the driver, which is a very nice alternative to MalwareinJoy)
Pokopom Xinput Pad Plugin 2.0
LilyPad-MotioninJoy (if you've a DS3 and are using MiJ)

Also if you don't want to use plugins, and want something that just werks, then use XEBRA, or RetroArch with Mednafen's core.

Or pSXfin, if you cannot get either of those running at all or are using a toaster for a computer. But be warned of possible compatibility issues.