Used to be Final Fantasy, now it's Persona. Suikoden was a contender but never quite got there because it's best game was still during the heyday of FF and it disappeared not long after FF got bad. You want 5 though? Um......Chrono and.... I don't know.

Tales? I really consider them pretty mediocre but fun. BoF? I really did like the BoF series, but top 5...I dunno. Mana? Secret of Mana is up there for me, but can I consider it a top 5 series when that's the only entry I really like? Wild Arms? I quite liked the first one, but... Ace Attorney? First non-RPG suggestion that comes to mind...I do quite enjoy them, but I don't know if it's THAT much, especially since the replay value is pretty low. Ditto for Zero Escape. Yoshi's Island? Well, I consider the first game to be the best pure platform game of all time, but as a series it's a bit redundant and declining in quality. I still enjoy them, but probably not enough to rank it as number 5 on my top 5 series. Zelda? Not for me, sorry. The original is possibly my favorite NES game, but Link to the Past, despite being arguably the best in the series, is only middling among SNES games. I hated Ocarina, didn't bother with most of the others, loved Breath of the Wild, but it's not quite enough to make the list. Xenogears? Isn't a series...and my hatred of Xenosaga is more than enough to cancel out any love for the Gears if I were to consider those. Dragon Quest? Just the fact that it took me this long to consider it despite currently playing DQXI is reason enough for me to realize it's not. Mega Man? It's a fun classic, but no. I'm always going to choose RPGs over that sort of game.

Okay, I'm just going to choose Breath of Fire.
Best in the series: BoFIII - I've already given my reasons in the poll on this. Best dragon transformations, best story. Possibly, best gameplay, although 4 has some additions that are kind of nice.
Worst: BoFVI - I haven't played this, but give me a break, it's manifest.

Chrono -
Best: Chrono Trigger. Obviously, this game is so eminently playable. Even without the extra endings and everything, the OG "New Game +" gave this game insane replay value and it's just a delight to play throughout.
Worst: Chrono Cross - I don't have the hatred for CC that some have, but there are a couple thing holding it back, and they aren't the complaints a lot of CT fans have. One was the gameplay. Although not terrible, the overly complex level structure for the techniques weighs this game down and pales in comparison to the charming simplicity of CT. The second was just how much of this game is devoted to fluff mandatory side quest nonsense. The main plot is great, IMO. It's just a shame how little of the game is actually directed to it.
Not counted: Radical Dreamers - This might be the worst, but I don't know it and I'm not counting it.

Suikoden -
Best: Suikoden II - This game has it all. Solid, simple classic RPG gameplay mechanics with great Suikoden series gimmicks like combos, parties of 6 with multiple rows. A large, diverse cast with much to see from the various members in the form of investigations and other interactions and a core cast that is among the best of any RPG. The story is engaging and emotional throughout. Absolutely, the best.
Worst: Suikoden IV - This game is utter nonsense and a shame on the series. It wouldn't even count as a mediocre RPG if it were separate from the series. The characters are dull, lifeless and uninteresting. The plot is meaningless drivel. They couldn't even get the gameplay right when all they would have had to do is copy the mechanics from earlier games in the series.

Persona - Best????? I don't know! I vacillate between Persona 3, Persona 4, and Persona 5 constantly! They each have their own charm, advantages, and disadvantages, and I adore each one. That said, if I must make a choice, it is Persona 5. While Persona 5 definitely has the drawback of being too easy, it seems to have perfected the format that was started in Persona 3. Now each Social Link is worked into the gameplay even more by adding skills in addition to the fusion bonuses. The story is fantastic, as it is with all 3 of them.
Worst: Revelations: Persona - This game isn't exactly bad..... except, you know, for the game part. I've never finished it and the reason is largely because the system is just an awful grind. To make new Personas you need persona cards. To get persona cards you have to have conversations with demons. The number of cards you need to make a single persona is often quite large. This necessitates having the same conversations over and over again. The experience is..... awful.

Final Fantasy- This is my original favorite series. I don't think much of the series or games released for it for over a decade, but the earlier games from the SNES to the beginning of the PS2 era remain among my favorite games and include my favorite of all time.
Best: Final Fantasy VII - I've changed my mind on my favorite entry in the series at various points, but I've always come back around to FFVII. It has staying power. While my love of FFIV is largely powered by pure nostalgia, this game really took the series to new heights at the beginning of the 32 bit era just as FFIV did in the SNES era. As much as people like to knock the blocky characters, the beautiful pre-rendered backgrounds easily beat anything we would later see in the PS2 era and still beat a lot of the real time rendered visuals we see today. I always lament Square's abandoning this style with FFX and beyond. Just because they didn't "need" them anymore, doesn't mean they shouldn't use them. The story was great. Although kind of jumbled by the bad translation, it was still an amazing ride working through Sephiroth and Jenova's deception and Cloud's own distortions to get to the truth. Aeris death was one of the most moving emotional events I've experienced in a game. There were deaths in Final Fantasy games I'd played before, but this one was truly shocking to the point I couldn't believe it. Sephiroth is just the consummate bad ass villain. The whole game is so atmospheric, it's just a joy to traverse the world.

Worst: Final Fantasy II - Who put Saga in my Final Fantasy? No, this isn't the happy marriage of a Reese's peanut butter cup. I'm pissed. This gameplay/level up system doesn't even deserve to exist and it certainly has no place in my beloved series.
Okay. That almost seems like a cheap shot though, because Final Fantasy II was so early in the series I can maybe give it a pass.

Therefore, while FFII might be the absolute worst, when grading on a curve, my true worst is:
Final Fantasy XII - Okay, now you have no excuse Square. This is such a marked decline in character and storytelling from previous entries in the series that it's inexcusable. The characters are flat, one note, bland garbage and most of them don't seem to have any business being there or any real connection to the plot. In fact, why are we even following these characters at all? Any actual plot the game has seems to be going on offscreen away from the characters. But thanks for lifelessly telling us about it in text, I guess. So when you finally come to the end boss and he's blabbering on about gods and his motivation it's completely unearned. You don't know this guy. The game barely shows you trout about him and this is the first time he's breathed any word about wanting to fight gods or whatever. It's utter rubbish. It's like someone just wrote down a cliche plot idea on a storyboard and then instead of actually fleshing that out into a narrative, they just decided to have the character shout the cliche at the end and said "that's good enough." Seriously, F you for the lack of effort on this. Then there's the gameplay. I really hate the gambit system for various reasons, but I just don't have the energy, because the storytelling on this is such trash, it sucked the life out of me.