best to worse
MGS1
MGS4
MGS:PW
MGS3
MGS2

Only going to list the main series. (From worst to best)

-Metal Gear Solid V: Ground Zeroes

It's on the bottom for being by far the shortest in the series. The gameplay is pretty top notch (although rather repetitive) but it's missing the plot and story progression that makes MGS so much fun in the place (and well doesn't supplement it with anything else). All of that is really because it's a prologue to Phantom Pain.

-Metal Gear Solid 2: Sons of Liberty

Sorry Wright. There's a lot to like about this game, namely the improved gameplay from MGS1, the music, graphics (pretty damn good for 2001) and the plot is also pretty interesting. But I can't shake the feeling that the game just feels unfinished, namely the latter part of the game and it's reflected in the pacing of the story. Also I thought the bosses for the most part weren't too great. Still all in all, a great game but it has some glaring issues.

-Metal Gear Solid

Out of all of them, the gameplay in this one is definitely the weakest. My first time playing it, it took some time to adjust to the clunky controls and movement. But there are a lot of things which I really like about MGS1, namely the plot and the atmosphere (excellent OST too). I find myself coming back to MGS1 a lot despite it's flaws, there's just something about it that I loved from the moment I first played it.

- Metal Gear Solid 4: Guns of the Patriots

This one is a blast to play, the gameplay is really solid (the best in the series thus far I think) and you have so many custiomization options for your guns. The locations are great, graphics still hold up really well, music is excellent and all the locations you visit are memorable (well most of them at least), and some of the best boss fights int he series. The main reason why this isn't my top pick is the series baggage. Having to tie up this entire series with one game is a massive challenge and as a result the plot is overbearing, confusing and downright ridiculous at times. It's a blemish on an otherwise amazing game.

- Metal Gear Solid 3: Snake Eater

Top of the list and one of my favourite games ever. Tight gameplay (along with moving MGS into the world of free cam), great music and good graphics. The environments were much more open compared to the claustrophobic environments of Shadow Moses and The Big Shell which was refreshing, it also feels like you have a lot more options available because of the environment (along with some new gagets). I also liked how you started in the jungle and had to make your way through to the base and survive along the way, it was a nice touch. Along with that, there were a range of environments from the jungle to the mountains and urban environments which kept things fresh. The story was very campy but also managed to have some emotional moments too and the cast was the best in the series, I really loved using the codec in this game. The bosses too, they were all very unique and just fun to fight I would say overall the best in the series. Definitely a game I will be coming back to for a long time.

Not sure how much sense my late night ramblings made but I really like MGS3.

MGS2 #1? *pukes*

From worst to best of the ones I've played

5. MGS2
4. Peace Walker
3. MGS
2. MGS4
1. MGS3

1 Peace Walker
2 MGS 3
3 MGS
4 MGS 2
5 MG 2 - Solid Snake
6 MGS 4
7 Portable Ops
8 MG

1.MGS3
2.MGS2
3.MGSPW
4/5.MGS4 and MGS1 (can't decided which i liked more)

I only care for canon games:

1- Metal Gear Solid 4: Guns of the Patriots
2- Metal Gear Solid 3: Snake Eater
3- Metal Gear Solid
4- Metal Gear 2: Solid Snake
5- Metal Gear Solid: Peace Walker
6- Metal Gear Solid 2: Sons of Liberty
7- Metal Gear Solid 5: Ground Zeroes
8- Metal Gear

For me its 3, PW, 2, 1. Havent played 4 and GZ is just V's Tanker mission.

1) MGS3
2) MGS PW
3) MGS2
4) MGS
5) MGS GZ

10) Portable Ops

-No voice acting

+/- can't tell much more since I haven't finished it

9) Metal Gear 1 (MSX)
+The game that started it all
+It introduces the stealth genre and many elements that are essencial to the saga
-The story itself is pretty short

8) Peace Walker
+Fun gameplay with lots of replay value
+Decent story overall and cool themes regarding war and AI, the ending is pretty awesome
+Developing motherbase is fun enough
-Villains are forgettable
-The story is on the short side
-I found characters such as Paz and the french lady having ridiculous voice acting.
-Mechas and bosses make annoying sounds

7) Ground Zeroes
+The best gameplay in the series at least until next week
+Awesome in every technical aspect
+The story is good enough as a prologue
+A lot of challenges that give it replay value
-No real development on the protagonist
-Shorter than anyone expected

6) Rising
+Fun and over the top gameplay
+Decent storytelling
-Not the real MGS Experience

5) Metal Gear 2: Solid Snake
+The game structure is very similar to MGS1
+Must be one of the first games with a long and coherent story with good character development
+Gameplay is innovative (MGS1 borrows a lot from it such as keycards, soliton radar, nikita, C4 and many more)
-8 or 16 bit graphics and sound, so no voice acting.

4) Sons of Liberty
+Hardcore philosophical themes towards the end.
+A huge improvement from MGS1 in every technical aspect.
+/- bosses are cool enough, but not the saga's strongest.
-Raiden can be annoying even when he has a cool backstory, Rose is even more annoying.
-The scenarios feel a little confined compared to other games.

3) Guns of Patriots
+Very nostalgic
+Cool dystopian plot elements and underlying themes
+Many beloved characters make a comeback after what felt like an eternity
-The flow of the game is somewhat irregular due to long cutscenes
-Sexiest bosses but with poor and cheap character development.

2) Snake Eater
+Emotional story with great plot twists
+Fun gameplay and extense world
+Cool portraying of a previous era
-Annoying gameplay elements such as healing system and camo
-Even though boss battles are cool (The End being awesome and innovative), the characters themselves are a little dull.

1) Metal Gear Solid
+Over the top plot with clones, cyborgs, cowboys, psychics, doppelgangers, shamans, evil twin, genetic engineering, nanotechnology, nukes and awesome plot twists, what else could anyone ask for?
+The best character development: friends, bosses and optional characters such as Nastasha have an extensive background and awesome dialogue.
+The largest supporting crew, every ally has something to say for most events in the game.
+Great music by TAPPY
+Realistic and natural voice acting
+Boss battles are innovative and gameplay is fun enough overall
+Revolutionary in many aspects (mainly narrative): way ahead of its time.
-Every technical aspect such as graphics, gameplay and sound quality haven't aged well.

Edit: Wow, that was long!

Of the ones I've played:

1. MGS4
2. MGS2
3. MGS
4. Peace Walker
5. MGS3
6. Ground Zeroes
7. Revenegeance

I recently finished MGS3 for the first time, and I don't know why, but it just didn't hook me like it does with everyone else. It was my 4th attempt at playing the game, as I always stopped right around when you get to Sokolov.

As for the other entries, I know there's a lot of cutscenes in MGS4, but I think it's an a amazing end to the story (technically), and it has my favourite gameplay in the series. I really like MGS2 for some reason, and MGS1 is just held back a little by the controls (seeing as I never played Twin Snakes). I'm currently playing PW, and I think it's really good. And finally, I think Revengeance is garbage.