My Perfect Marvel Cinematic Universe would probably be this:
Phase 1 (2008 - 2012)
- Iron Man - intro of Iron Man
- The Incredible Hulk - intro of Hulk
- Iron Man 2 - first sequel | first sequel with a number
- Thor - Intro of Thor
- Captain America: The First Avenger - intro of Capt. America
- The Avengers/Avengers Assemble - first team-up
Phase 2 (2013 - 2015)
- Iron Man 3 - final Iron Man movie
- Thor: The Dark World - sets up some plot points for Guardians
- Captain America: The Winter Soldier - sets up some plot points for Avengers: Ultron
- Guardians of the Galaxy - intro of the Guardians
- Avengers: Age of Ultron - second team-up
Phase 3 (2015 - 2018)
- Ant-Man - intro of Ant-Man
- Thor: (subtitle) - final Thor movie | ties in strongly with Guardians 2
- Guardians of the Galaxy 2 - sets up some plot points for third Avengers movie
- Captain America: (subtitle) - final Capt. America movie | sets up some plot points for third Avengers movie
- The Incredible Hulk: (subtitle) - final Hulk movie | goes directly into third Avengers movie
- Avengers: (subtitle) - final Avengers movie | Avengers+Guardians team-up.
- Agents of S.H.I.E.L.D. - series only lasts for the duration of Phase 2 | sets up some plot points for Avengers: Ultron
- Agent Carter - airs before and after third Capt. America movie | sets up plot points of said movie.
- TV series set in space - lasts for the duration of Phase 3 | sets up some plot points for third Avengers movie
Agents only lasts until Avengers: Ultron is shown as both are set around S.H.I.E.L.D. as does the second Capt. America movie.
Only Iron Man movies have umbers in their sequels, all others have subtitles. Guardians would be too long a title for a subtitle so Guardians of the Galaxy 2 fits fine.
Guardians 2 connects strongly with third Thor movie because both set in space and both right next to each other.
Guardians team with Avengers in third Avengers movie because it is the final MCU movie and would seem unlikley the first Guardians movie will tie in much with rest of Avengers series.
Marvel Cinematic Universe would start in 2008 and finnish in 2018 making the entire franchise last a nice ten years.