I'm honestly not sure on the reputation of 4 overall from the fan base but when I first played it I personally adored it, even with all the cut-scenes, kept me hooked enough it didn't bother me (was a late night though with the length of those final cut-scenes
).
Twin Snakes I'd love to play myself as well, only played a little of Portable Ops but I currently don't have a working PSP so my copy is unplayable atm, was fine from what I remember. I've played a little of Acid but couldn't get into it personally, would give it another shot though, was much younger back then. Ghost Babel even though non-canon I'd like to see get a re-release just as it's a bit obscure and would just be neat to have as many games from the series as possible available, even if just via Switch Online.