I have zero opinion on the matter, as I'm not a fan of either, but judging from most of the anime I have seen, isn't this largely a plus?

There are good anime adaptations but mostly are shit... and the fillers... OMG the fillers are terrible.

It is like books vs movies... even great adaptations suffers in quality compared with books.

During my years of being an avid Anime watcher I went to numerous transformations.

One of which was purporting that anime was infinitely superior to manga because of the whole color, movement, music and voice stuff. It still holds up for some stuff but manga is as equally viable for entertainment as anime.
In my life I read like 10 mangas but watched hundreds of animes. I will still choose anime over manga but there are some advantages for manga:

Art
It's immediately visible that most manga just have better art than their anime counterparts. That's of course because it's much harder to animate art than to do still images. It's a big plus though and even though it doesn't move and is without color it really is stunning. One example of my favorite manga.
http://img3.wikia.nocookie.net/__cb20091118111608/claymore/images/0/0a/Isleay_awakened.jpg
This just isn't possible with anime. Another thing is that certain emotions are better shown in a still image than animated. The expressions in manga are sometimes much more nuanced and subtle.

Pacing
This was one of my alltime best arguments for anime. Pacing is extremely important to invoke immotion(especially humor). I always thought manga was clearly lacking in that part because the creator would not be able to control the reading speed of the reader.This isn't completely true though. There are a lot of ways to pace the reader and make them awe at specific parts. It works for some reason even with comedy.

Continuity
This is probably the biggest selling point and the reason why I would even pick up a manga. Animes are mostly just vehicles for the original media it was on. Basically a glorified commercial for the manga or novell. They are severely money constrained planned ahead. That's why a lot of animes don't get a conclusion like mangas or even worse, get a conclusion that is not part of the original work just because the anime has to end. Claymore is one of the worst offenders of this. They shoehorned an ending into the anime when it was maybe a quarter into the real story, effectively eliminating any chance for a continuation of the anime. This practically forced me to read the manga and boy was I surprised. Not only did the manga have all this gorgeous art that painted the world in a much more gruesome fashion it also delivered the real continuation of the story with even more plot twists than the anime.

Emotion
This isn't really an advantage for manga as it is simply a lot easier for anime to evoke emotion than any other medium because it can attack the full range of human senses for that.

The point is that even though everything is against it, manga is actually able to evoke strong emotions. A thing I wouldn't have thought of being possible. But then the moment came where I simply couldn't move on reading Claymore because my favorite character was about to die. I just couldn't. I had to put it down for over a year until I felt strong enough to pick it up again. And when I did it brought actual tears to my eyes. Even writing this I'm about to cry over it.

No distractions

As much as anime has going for it, all of its different elements are potential distractors. Shoddy animation, weird color schemes, annoying voices, lacking music, ridiculous censorship, awful script. All of this may take away from your experience. That's why its a lot harder to produce a good anime than a manga. It's also a lot harder for anime to do exposition. It's common and easy to pull off in manga since you're reading anyway but it can utterly ruin an anime with exposition dumps.

So in conclusion, people who either say that anime or manga are best are both wrong. They are equally viable depending on how they're made.

To answer your other question, in my early anime watching days I stayed clear from ongoing seasons and only watched finished animes for obvious reasons. As my lust for anime became bigger and my "to watch" list ever longer I started watching seasonal anime. It's a great way to not get behind as it practically forces you to watch anime every day. And if I have free time in between I watch finished animes from my watch list. Because I'm watching every season(about 25+ animes) my watch list doesn't grow anymore.

Fairy Tail!!! Damn ever since the Grand Magic Games Arc, the quality been down

Fairy Tail is still in my top 10 manga's though. Animation in the show is one of the best i must admit, unlike my favorite manga of all time (One Piece), which Anime is complete garbage now (Sooo sad)

Animation is good, but the problem is right before the time skip, the anime  started to do 1 chapter per episode ratio. Its wayy to slow, but you should def watch it!

Edit: You watched the anime, do you remember Sanji's Flashback?

I've always been a far bigger fan of cartoons than comics, so i favor the anime. That said, anime adaptations of manga can sometimes be bad for the anime, as they try to fit into the constraints of the manga's release schedule, but this is a problem more limited to anime adaptations of long-running manga.

Your sig makes me want a donut...

Glad you ask!

Anime: Zeff (Guy who owns the boat restaurant+Saved Sanji) leg was caught while going under the sea and had to break his leg off to survive and save sanji (making him a one legged man). Then while trapped on that rock, He gives all the food to sanji in one bag while secretly holding treasure (made sanji think it was his own food and much bigger portions) in the other bag. after weeks of starvation, Sanji realizes Zeff gave him all the food while Zeff had none for himself.

Manga: Zeff leg was never caught under water but still saved Sanji and went to the rock they were trapped on. So How did Zeff lose his leg really??? Well same scenario as above happened while trapped on the rock (with the two bags, gave the food to sanji, the other bag was treasure), but in order for Zeff not to starve himself (cuz he gave all his food to sanji) he cut off his own leg and ate it O.o!!!!

A classic example...

Saint Seiya.

Anime: All Mitsumasa Kido's knights are orphans.
Manga: All Mitsumasa Kido's knights are brothers and his childrens with different mothers (Ikki and and Shun have the same mother too).

In the manga he just go to every place of the world to make childrens to train to become bronze knights... he is not a good person like the anime shows... he didn't give a fuck to the mothers... and his intentions to make knights was not to save the world lol but it was to his own benefit.

Ohhhhhh the first Fullmetal's anime was a way different history from the original manga... just the very begin was similar... the anime even finished before the manga ended.