I considered not taking part but here we are with my controversial opinions.
Metal GearBest - Metal Gear Solid V: Phantom Pain. I'd love to say I'm biased because V was the first one I played through entirely, but I just didn't enjoy the controls from the older games and QoL wise they are pretty hard to go back to. I did beat Metal Gear and I had played Metal Gear Solid 1/2 before the release of MGSV, so I know I just didn't enjoy the original controls. like I loved Resident Evil 2, but I can't say it's the best because the controls make it hard to go back to. All that said, MGSV has so much in the way of QoL improvements over previous entries and just is an amazing game to play mechanically. I know I've seen the complaints about the move away from the traditional structure of MGS games, but I'm honestly a huge fan of the traditional structure, so I enjoy this game. This game lets you choose to do missions in so many different ways, it's very open in that sense.
Worst - Metal Gear Solid 4. I'd love to say Metal Gear was the worst, but it's hard to judge a game that I only remember as being so old, so I choose to ignore it. MGS4, however, being a modern game, was just terrible at both sides. It didn't do stealth very well and it didn't do action very well. I know my playthrough I couldn't get through anything without setting off alarms and such, no clue what that was about and the controls were atrocious for the action side. It was a step in the right direction of gaining more casual consumers, but I think it just confused everyone.
Final FantasyI'm gonna be super controversial with this one
Best - VIIR/XV. I had initially written XV, because I forgot 7R existed. I enjoyed the crap outta XV, so much so that I played until I got the platinum trophy. Functionally (ignoring the car) XV and 7R are similar games, 7R is amazing because of the characters and world, but it loses points for being a fraction of the story and it does in fact have its frustrating moments. XV is amazing because of the characters and world as well, but it loses points for the car and car related things... mostly the fast travel costing money, not using fast travel having auto-drive but still taking forever as like a punishment, and the inability to like drive if a monster shows up. That being said, again the QoL improvements by a more action oriented system make these two games the best. I've never been a fan of the traditional "turn based" ATB system, ATB system works moderately well in an action oriented combat system.
Worst - VI. I'd love to say 8 is the worst, but I honestly haven't ever played 8. Maybe I'll play 8 one day and it can earn its place as the worst, because of its stupid system where enemies and bosses level with you so grinding can actually make the game harder.
That said, 6 is pretty fucking terrible. High encounter rates, low xp gains, revolving team members, confusing menus and mechanics. Sabin's skills can waste turns. Gao requires sending him off on a grind to learn new moves. So many instant kill enemies that you have to dump all your gil/gold into phoenix downs. Just an unenjoyable experience.
YazukaBest - 5. This game has a lot of the major QoL improvements of late entries to the series, but it has so much content, character, and story. Don't get me wrong, 6 is great, but it's short. 0 is pretty amazing, but it falls just a bit short of 5.
Worst - Dead Souls, 1, FotNS. I threw 3. Dead Souls being the first worst for just being almost irrelevent. 1 for being the oldest and lowest QoL of the mainline entries plus terrible VO. FotNS because I just couldn't get into it, I really wanted to, but it just felt wrong.
Resident EvilBest - 2 Remake. I wanted to put 3, but 3 is shorter and has more of the frustrating things that 2 had. Overall an amazing remake and I look forward to future titles in this vein.
Worst - 0/6. 0, I consider the worst for it just being so dated. 6 for being just not a Resident Evil game and more like Army of Two or something. 6 might honestly win, for just being a waste of time largely.
Mega Man XBest - X. I know I'm biased, I like X
Worst - X7.
ZeldaBest - Breath of the Wild
Worst - Zelda 2
BattlefieldBest - Battlefield 1. The story mode was amazing
Worst - Battlefield 2: Modern Combat. Gawd was this game atrocious
Need for SpeedBest - Most Wanted (2005)
Worst - Need for Speed (The recent reboot)
Super MarioBest: Super Mario World
Worst: Super Mario Bros 2.
SoulsborneBest - Dark Souls (Remastered)
Worst - Dark Souls III