ENJOYABLE FACTOR RANK
1. Terminator 2: Judgment Day (1991)
2. The Terminator (1984)
3. Terminator 3: Rise of the Machines (2003)
4. Terminator Salvation (2009)
OBJECTIVE RANK (CONSIDERING ORIGINALITY, COMPLETENESS, LACK OF PLOTHOLES, ETC.)
1. The Terminator (1984)
2. Terminator 2: Judgment Day (1991)
3. Terminator Salvation (2009)
4. Terminator 3: Rise of the Machines (2003)
I enjoy watching T3 more than T4, but I think the Christian Bale film is objectively superior because T3 is basically just a rehash of T2. Also, I enjoyed T2 more than T1, but T2 has so many plotholes and has a lot of cliched dialog and themes.
I wouldn't split them up like that. Movies are made ENJOYABLE by originality, completeness etc)
I'd rank them like this:
Terminator 2: Judgment Day (1991) - 10/10
The Terminator (1984) - 9.5/10
Terminator 3: Rise of the Machines (2003) - 7/10
Terminator Salvation (2009) - 7/10