Meh.

I'd like if they stool to the manga, but I like evolved storylines

as long as the plot is legit though

There are some animes where I'm fine with the anime-only ending and branching off from the manga.
Like Ouran Highschool Host Club. It branches away from the manga a bit but it's still a pretty damn good anime.
Now, there are some anime that are okay up until the ending, which just seems rushed and pretty flat. Examples of this are Blue Exorcist (although they're continuing again from the Impure King arc and ignoring the added-on shiz) and Soul Eater, and manga fans were very displeased with the ending for BE (although people that only saw the anime seemed okay with it, honestly it felt unfinished when I first watched it), and most people seem to just generally think the Soul Eater ending was rushed, cliched, and hardly made any damn sense whatsoever.

So while some anime is okay to branch off, some of them do the job poorly and are just rushed so they can finish the anime on time instead of delaying it and possibly causing the fans to be salty about waiting for it.
And Blue Exorcist had an anime only ending and stopped following the manga because Kazue Kato travels a lot and wasn't writing for a while, so they basically had to whip up something so the anime didn't go unfinished.

Like mai choice says it depends. I like an anime if the new ideas are good but I typically like it to stick with the manga.

The manga is canon. So i much prefer that it'd stick to the manga because that's what really happens.
The only time i prefered the anime ending to that of the manga is in death note. As much as i hate Light, the ending of the manga was just too cruel :/

"The manga is canon. So i much prefer that it'd stick to the manga because that's what really happens."

^THIS