Best subtitle extension?

[Skullchukka]

Hello. I'm the head of a small translators circle who focuses on 07th Expansion's works, and translates them into Turkish. We'd like to stay as legal as possible, that's why we don't do fansub releases, so we use another [English] groups release, and use their subtitle.

As the title suggests, I'm looking for the best subtitle extension. Since I will most likely get "there is no best extension, all have their cons and pros", I will ask you to make a suggestion, and use a list such as;

Srt extensions -
Cons:

• 1
• 2
• 3

Pros:

• 1
• 2
• 3
• 4

I personally always used srt extensions. Not because I'm familiar with all others and I preferred to use it, but because it was the most simple one when I first started. But now I come across some small details that just tick me off, such as;

• You can't have 2 people speaking at the same time.
• You can't add Translator Notes.

So, I'm in a way, looking for an alternative. I tend to use ass formats, but there may be down sides of using such extension, and I'd like to know beforehand, before changing our subtitles for the existing & future projects.

Thanks in advance,
Skullchukka of Furude Project.