Of course they can be ranked, but with a high level of subjectivity. You say FFXIII has broken combat, to me it's one of the best gameplay I saw in a modern RPG. It is fluid and challenging even against mobs, you can't just go and press the attack command while doing something else against mobs. The leveling system was interesting and permitted a nice customization, depending on your playstyle. I hated FFVIII tough.

But any post IV FF have some common ground : 

Great OST (anyone saying One winged Angel never listened to Dancing Mad <3 (half joke))

Great design, especially on monsters and environement, while character design is subjective (I hate both amano and Yoshida, while I am a big fan of Nomura's work)

The game revolves around a good/great storyline in a complex universe, with elements of both Scifi and Fantasy (And some prefers the emphasis on fantasy (X), or scifi (XIII) )

Big budget and impressive tech in their time (FFVII = 3D, X = facial animation, ...)

So despite everyone having preferences, these game have a lot in common and the same staff behind them, wich makes them all at least good, objectively.

And popularity has nothing to do with being a great game or not. Most FFVII popularity came from the fact it was the first big 3D RPG. Impressive tech can sell a meh game.

A good example would be Rayman Legends. It is objectively better than Origins : Same gameplay, design but better Res, animations, and above all content. It didn't prevent Legends from a big fat flop, due to bad advertising and bad release date.

Nostalgia googles. Even for the time PS1 era FFs had shitty in game graphics, VIII had a bad gameplay, VII had a simplistic storyline with fake twist directly directed at tweens, IX had terrible load time for battles (That was horrible), endless grinding postgame, ...

Character design improved with time, OST are still as great as VI was, Monster design as improved, Gameplay is now really active (You don't have half an hour to think about what you will do next (For example in VII -> X I know beforehand how I will handle the next 30 minutes of random encounters) ).

Pre PS1 Era already had what made PS1 era great, except 3D and cutscenes to impress kids. Just saying.

I do think something VII related will be released in 2017 for its 20th anniversary. Not the remake per say, but maybe the sequel to Dirge. The ending to that game leaves room for more in the VII universe.

I'd hope not, even that game 'ruined' the ending of FFVII, secret ending (or what I presumed was a result from using Holy) should have happened.

On subject, any remake would be bad, voices, 3rd person movement, non-japanese character design, I can see it all happening.

Yes.....for mobile platforms. 30$ + microtransactions for Materia

I actually wouldn't mind this either. I still haven't gotten to play FF VII, and I imagine it could be made to look pretty good on the 3DS if the games I've played so far are any indication.

Edit: That said, I do get why people would prefer it on a console. Ignoring the HD aspect for a moment, the feeling of playing on the big screen versus a handheld is always al ittle different, and for a game that started out for a home console, shrinking it down (physically, anyway) to the 3DS screen might seem like a slap in the face. Mind you, I love handheld gaming, so it wouldn't bother me, but I think it's worth mentioning. 

Well if MS did get exclusivity I think everyone would be questioning if they want to lose money, how much MS paid them and/or if they care about their reputation at all. As for if it was on both consoles, I wouldn't frankly care as long as I don't have to buy another system to play it and they don't sacrifice any quality of the game bringing it to two consoles instead of one. I don't know how many people cried foul when it was said that KHIII was announced for XOne and PS4 but I always believed that the few ignorant cry the loudest. It doesn't mean that the whole fanbase believes it.

Well, that's a slightly different situation than what we have here.  It wasn't that Sony paid for the exclusivity, it was that Nintendo abandoned the Super Famicom CD Rom joint venture between themselves, Sony and Phillips.  They decided that they were going with the cartridge solution again with the N64, and Square wanted the CD Rom solution, because it provided them more room to work with.  That, I can kinda understand, if the game you're envisioning can't be done on cartridge, you gotta find another option.

Its not nostalgia at all. Its completely logic. Due to 3D assets beeing more costly to develop with the coming gens alot of parts from JRPG's have been cut. The interactive world maps, the number of locations, the ammount of events and storyline (due to voice acting).

Most series have disappeared or declined cause they lost their quality. The persona series is the exception and while the Tales series perseveres its also falling prey to some of those pitfalls.

Now for details, I agree that FFVIII had crappy gameplay at the time (i hated the draw system) but after seeing XIII it somehow doesnt seem as bad at it was. VII definitly does not have a simplistic storyline. I dunno what you are on about. I find most soundtracks are not nearly as memorable as they used to be. Again, only Persona pops to mind as the exception.

As for character desing, its debatable since its up to personal taste. I have no complaints in that department.

You didn't know? Sqaure Enix doesn't care about anyone anymore.

They do what they want, when they want.