Whenever I get my computer back in action, I must remember to play that Strange Aeons Doom wad. Love the mix of Quake/Chasm along with the Cthulhu mytho inspiration. One of the replacements for the weapons is an AK47 for the Chaingun and it's awesome. There is plenty of ambiance in the music which reminded me of PSX Doom and the level designs are truly strange. Sometimes you'll receive assistance from ally Revenants called Ghouls and they will kill enemies for you with their railguns. Overall, I love the style of this Doom wad.
I still remember my first Doom megawad, I think it was 2002: A Doom Odyssey for Ultimate Doom. At the time I was unaware of source ports so I made a poor attempt to run through Doom95. The first port I downloaded was Doom Legacy and I still think it is an okay port. But now I use ZDoom and eventually I played 2002ADO using it much to my enjoyment. There are so many mods for Doom it is pretty crazy, you will almost never get bored with Doom if you like fan-made content.