by far the best is pSX. yes epsxe has enhanced graphics but it also cause alot more graphics glitches as a result as well. pSX just gives you the original systems graphics raw and untampered with. if you want accurate emulation that should be what you want.
pSX also doesnt require a lot of configuring to get it set up ether. you just set up your controller, point to your bios, make a memory card and off you go. no need to have different configurations for differnt games. it just works. simple. another good thing is there's no plug ins to worry about. the emulator is all self contained.
compatibility seems better than epsxe. I haven't found a game it wouldn't play
Psx contains a disk image conversion feature where it can convert a disk image to its own unique image format that compresses the image saving you disk space if you wind up wanting or needing more room.
to top it off the developer of pSX is working on integrating ps2 emulation into pSX and word is hese already got one game running already although noone realy knows what that game is so the future looks promising for this emulator.
system requirements are low so more systems can run games without issues and since the graphics are done in software there is no differance in performance between a low end graphics card and a high end one. for all you Intel integrated graphics users this emulator will run great.
I could go on and on but why dont you just give it a try for yourself . don't forget to pick up ultima's pSX front end for the best experience