Well, Romero did design ‘Sigil’ with GZDoom in mind, so in this particular case it's fine to use a high resolution as he probably arranged the visual details and engagement ranges with that in mind. It was clear from official screenshots that he was using the software renderer, though. Otherwise though, yes, I believe it's best to play the original games at 320x200 and at 35 frames per second.
I'll try switching to software mode just to see how it is. But still, I like GZdoom because of how fluid it feels on 144hz monitor. Also, I found a mod called Vsmooth that adds additional frames to weapons without changing anything else. It's smooth as butter. Some mods like Smooth Doom change too much for my taste. Also, the minimal HUD in GZdoom is nice. Together with perkristian HQ sound effects and Patch93's SC-55 soundfont, I think I've turned Doom into the best vanilla+ experience it can be.
Well, it's worth keeping in mind that the original games at least were intentionally locked at 35 frames even though it wasn't an inherent hardware limitation. All those mods are fine for replays, but I wouldn't change anything about the original feel.
As for the soundfont, if you mean the MIDI music in ‘Sigil’ specifically, it seems like Paddock composed it with Microsoft's default MIDI player in mind:
SIGIL - The MIDI Soundtrack | James Paddock (bandcamp.com). Not that those samples sound very good ...
Otherwise, when it's not a question of custom MIDI tracks, there's no reason not to use the SC-55 packs with GZDoom as that's as authentic as it can get. As for other MIDI music, it's also worth keeping in mind that one soundfont isn't necessarily best in all cases. One notable example is
Heretic, the music of which was apparently composed on Sound Blaster AWE32 and it does sound much better on it than on SC-55, but unfortunately there's no decent substitute for the card:
(time-stamp at 24:40)
There's a play-list with all the tracks recorded on AWE32, but the quality is quite poor unfortunately:
https://youtu.be/clhPypC4naA?list=PLr88YJ3aDghtnJ2LW_wP1qAjf-JzVCDUx
(
Hexen's music was composed on some derivative of SC-55, though.)
Truly the best FPS ever made, and it will never be surpassed.
It truly is. I used to be dismissive of it for a long time, assuming it was too basic or inherently limited in one way or another, but when I finally played it properly I was amazed at how good the gameplay and feel of it were.
EDIT: For comparison, here's the same part but taken in the Unity port. It's not that bad tbh. But that port has other problems: shitty MIDI reproduction, locked to 60fps, movement feels weird, mouse acceleration. It they manage to fix it, I wouldn't even bother with source ports for vanilla playthroughs.
That's a shame about the port, I thought it might be something that could be recommended to others as a simpler solution. About the weird movement though, note that
Doom had rather strong forwards and backwards mouse-pan movement, which is considerably decreased in GZDoom by default. It does actually feel good to play it with that original set-up as it allows for very fine and flowing movement and complements the keyboard input nicely.
