1000 vs 2000 SERIES

The original PlayStation Vita (PCH-1000) features an OLED screen, while the newer slim model (PCH-2000) uses an LCD screen. The main differences between the two screen types are:

Contrast Ratio: OLED screens generally offer superior contrast ratios with deeper blacks compared to LCD screens.
Color Accuracy: OLED screens often provide better color accuracy and more vibrant colors.
Viewing Angles: OLED screens typically have wider and better viewing angles than LCD screens.
Burn-in: OLED screens can be more susceptible to burn-in over time, while LCD screens are less prone to this issue.
Lifespan: The lifespan of OLED screens might be shorter compared to LCD screens.
Size: The OLED model is thicker than the LCD model.

While the OLED screen is considered superior by many due to its vibrant colors and deep blacks, some users may prefer the LCD screen for its potentially longer lifespan and reduced risk of burn-in.

Another difference between the Vita 1000 and 2000 is that the 1000 does not have any internal storage where as the 2000 has access to 1gb of user available storage by default. However, during the jailbreak process you can unlock the same 1gb storage in the 1000 (here).

The 1000 series has a none standard charge port where as the 2000 uses Micro USB.

PSTV / VITA TV

The PSTV is fundamentally a 2000 series but with changes and limitations, the first being that is not a portable device and needs to be connected to a hdmi input, secondly theres no controls so you will need a compatible PS3/PS4 controller, finally there is no touchscreen.
By default the PSTV does not support all games and applications due to hardware limits so developers lock them out. you can use plugins to remove this lock but you may still have issues depending on your useage. Like the 2000, the PSTV has 1gb of user storage.

1000 Series ( Phat / OLED )

2000 SEries ( slim / lcd )

pstv / vita tv

which is the best vita ?

There isnt a simple answer to this as they both have their good and bad points, where the OLED offers a better image quality the SLIM offers better connectivity, the SLIM is lightweight but the OLED could feel better in the hand. I will say that the SLIM does potentially have the edge when you look at all aspects, but both are very capable devices and either one will be fine.