Do you prefer to play a game as designed first, and add mods on the 2nd playthrough? Or do you implement mods right away for a more personalized experience?
Depends very much on the games and mods When a game is just release there often isn't something to mod, but if I play a game only later then cosmetic mods are fine to use right away, while mods that really change up the game normally have to wait for a 2nd playtrough, there are exceptions tho...
Well usually vanilla games are lacking of ... something, and if it is grindy then mods are landing pretty fast.
On the other hand... there was a reason why someone take some time to make mod for game... right?
Depends on the game. In general, 90% of the time, I prefer the vanilla version. Disclaimer, I don't consider VNs as full-fledged games, and KN is somewhere on the scrap heap for me.
Depends for example I played Baldur's Gate 3 without mods and I'm waiting a few months to start a modded playthrough, but other games if there's something I immediately want to change or annoys me I just mod it
First time playing is with a minimum of mods, usually just QoL mods that the community strongly recommends. Mods come in after enough playtime that I can understand what they are doing.
Vanilla mod. The feeling of the intended game design is best felt firsthand before anything else. I personally prefer to have the aesthetic cutscene of the original model, scripts, and glitches if any on first playthrough. On second playthrough though... God help me with the atrocious amount of mods I'm about to load onto this game~~~
I'd check for essential mods first according to general consensus and probably download those.
The rest I'd decide what I wanted to tweak based on my gameplay so probably would be second playthrough (or add them in mid-playthrough if safe)