So the only Metal Gear game I've ever actually played was the 1998 Metal Gear Solid for the PS1 when I was a kid. I've not played a single other game in the series since.
Which ones would you recommend? Would it be better to play them in chronological order to get the full overarching story, or do they work ok independent of one another?
Others will have more nuanced and insightful opinions, but I will say that MGS 1, 2, and 3 are must-plays and should be played in release order. It preserves the impact of each narrative as originally intended, which in a series like this is very important. MGS 2 is a masterpiece, but MGS 3 is one of my personal favorite games for the setting, story, bosses, gameplay, and absolute banger of a theme song.
MGS 4 is fine of you want to see the continuation of Solid Snake's story, but it gets more bloated than the previous games and didn't satisfy as well IMO.
I don't have as much experience with the series after that outside of Peace Walker, but be prepared for some big changes in terms of narrative and gameplay if you decide to keep going.