I'm a lifelong JRPG fan who's played just about every 16 and 32 bit RPG there is. Massive fan of anything Square, can tell you just about anything about the first 12 Final Fantasy games, etc. I've even beaten some really obscure shit like Paladin's Quest. But one series I never played was SMT.
First off, the only way to play almost all of the games in English is fan translations, and I tend to shy away from that sort of thing because they're often crappy. So if there are any really good translations out there, that'd help.
Second, they had a reputation for being grindy. I can handle a certain amount of grinding. Dragon Quest games are about where my limit is. I like DQ for the most part, but I don't like walking back and forth just outside of town, mindlessly mashing "A" for hours, and most of them devolve into just that around the halfway mark. I haven't played anything newer than 5 though, so that may have changed over time. Basically, if SMT is any less grindy than the early DQ games, I'm good to go.
Third, I don't really know where to start. I've got forty years of content to sift through. Do I play the DDS games? Do they hold up? I'd be playing the SNES remakes, almost certainly. How about the side games like Nine and If?
Oh, and for what it's worth, I didn't like Persona 4 at all. The level design was insanely bland (nothing but identical hallways) and the battles were too easy. But I've heard P4 is the least SMT-like of the Persona games, so that might not be a problem.
Personally, I think Persona 4 is probably the worst Persona game, but gets this high reputation because it was a lot of normies first step into the non-mainstream JRPGs like FF and the SNES ones of old. Its literally only good if you like to self insert as a Chad Thundercock with no problems and love the color yellow.
As for the non-Personas, SMT 3 is probably the best middle ground to test the waters on if you'll want to go deeper. Its got just enough grind, hardness, and lack of handholding to show you its not quite like other JRPGs but isn't a roughly translated game from an era where suffering was expected.
Well the good news is that isn't usually an option! If you are grinding its very likely that you'll get still having to put in a moderate amount of effort into every fight for your pittance of exp. Either because you don't want to spend your very limited SP (and either lose money on items or have to treck back to recover somewhere) or because they are just that difficult.
The thing is, that only happened years later. It was barely discussed at the time of release because we all just fucking understood it.
The biggest fight then was whether Adachi was a neckbeard (this being pre-incel) loser or a super based prophet. Which still goes on to this day and was strong enough to get him a special ending in Golden.