You should take into account resolution, lumens, and connectivity. All three of these factors are important because they play a key role in determining the quality of your viewing experience.
Resolution is one of the key factors to consider while buying a projector. The resolution of a projector is the number of pixels it is capable of producing and displaying. For example, a 1080p projector can produce 1080 pixel images. Resolution is the pixel count of an image.
The resolution of a projector is always quoted as a number of pixels. As you go higher in resolution, the number of pixels increases, and hence the overall image is sharper and more detailed. If you see a projector with a higher resolution than another, it means that it can display more detailed images, which is a good thing. In general.
if you are buying a projector for home theater, you should go for 1080p, as it is the most common resolution nowadays and can be viewed from a reasonable distance, unlike 4k (which is much sharper).
Lumens are the measurement of how much light a projector can emit. It is like the unit of measurement for how bright a projector is. Technically, one lumen is equal to one candela per square meter.
It is usually used as a measure of light output for projectors and video displays. It is very important for you to consider the lumens of a projector when you are in the market for a new one. So, how do you determine the lumens of a projector? As a rule of thumb, the brighter the better. You may have noticed the term "brightness" when shopping for projectors or displays.
The connectivity of a projector is what allows you to connect your projector to devices like computers, laptops, smartphones, Blu-ray players, gaming consoles, etc.
The connectivity is what allows you to get your content onto the screen. The better the connectivity, the more devices you can connect to the projector.
As a rule of thumb, the better the connectivity, the more expensive the projector will be. You'll want to ask yourself what kind of content you'll be projecting, and how you'll be projecting it.