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There is no perfect technology but each one has its positives and negatives. This can be a determining factor in selecting a projector. It is nevertheless important to figure out the higher end the unit, the more efforts are made by manufacturers to overcome the technology drawback.
As an illustration, LCD technology is known for not being the best in black level due to its operating nature. The high end Epson (UB) does not suffer from poor black level, but it is even said to rival or exceed similarly priced DLP units.
The bottom line: below information is generally speaking but is neither a universal guide to technology limitations nor works exhaustively for all models. It is just the pros and cons of each technology in general.

The main types of projectors are:
• CRT (Cathodic Ray Tube)
• LCD (Liquid Crystal Display)
• DLP (Digital light processing)
• LCoS (Liquid Crystal on Silicon)

• CRT:
This is the oldest projection technology and it works basically like our old televisions. The difference is the primary colors (Red, Green and Blue) are displayed through 3 independent CRTs coupled with a lens. Contrarily to other technologies, it does not have a single native resolution and therefore it is an excellent choice for displaying different source materials.

Pros:
- Unfixed pixel field resolution
- No screen door effect
- Best (deepest) blacks
- Long life (up to 20000 Hours or more)


Cons:
- Large and heavy (as big as a 20" TV)
- Costs much more than other technologies
- If a CRT fails all of them have to be replaced to re-establish a balanced picture.
- Precise alignment or RGB CRTs are required to avoid halos (most of the time requires a professional)

• LCD:
It is about passing a light from a bulb through transparent LCD chip(s) and then projected through a lens. This is first digital technology that was made commercially available

Pros:
- Small/compact
- More installation flexibility
- High color accuracy (3LCD)
- Low power consumption
- Bright
- Inexpensive

Cons:
- Screen door effect
- Not the best blacks
- Pixels are prone to burn-out
- Lamp replacement periodically required

• DLP:

This technology works with switching DMD (digital micro-mirror device). Available in 1 or 2 Million / unit which determines the projector resolution, these mirrors modulate the reflected light according to the incoming video signal.

Pros
- Small/compact
- No screen door effect
- Excellent color accuracy
- High Brightness and native contrast ratio
- Low power consumption

Cons:
- Rainbow effect
- Lamp replacement periodically required
- More expensive than LCD


• LCoS:

Liquid Crystal on Silicon technology can be considered as a combination between LCD and DLP technologies where liquid crystals are applied to a reflective mirror substrate.

Pros

- High pixel fill rate, no screendoor effect
- Excellent color accuracy
- No rainbow effect due to no color wheel

Cons
- Relatively lower contrast ratio
- Limited lamp life (1000-2000 Hours)

What does all that tell us? Here are some examples:

- If you don't have the necessary space or don't want to spend a fortune CRT is probably not for you.
- If you want an entry projector with acceptable black level, you may want to target a DLP projector
- If you're sensitive to rainbow effect and looking for a native 1080p projector, LCD might do….And so on, But But But, the assessment at this stage is far from being complete… keep on reading!