In US market $2000 can get you a decent ebike, not just a kit.
If you insist on a kit... You have to specify your needs.
A lot of steep hills - get a kit with mid-drive or a geared hub motor. (I don't remember if there are any mid-drives 250W, mostly they are 350W and higher).
Flat roads and moderate hills - get a direct drive hub motor or a geared hub. Direct drives tend to last longer than a geared hub.
Long distance without charging - get a bigger battery (hard to tell how big, I would suggest at least 360 WH, unless your trips are very short under 10 km).
Other details are minor (IMO):
There can be cadence sensor (motor assist depends on how fast you rotate the pedals), or a torque sensor (motor assist depends on how much effort you put into pedaling). With either type there can be a "Throttle" option, when you hit the button and motor runs without any pedaling - this option is not allowed in some areas, check your local traffic laws. Some motors don't have a Throttle option, but most of them do.
There is only about a dozen of reputable motor brands (if not less).
To give you an idea of types of motors and other components, here is a place in the US:
https://lunacycle.com/motors/. No affiliation, never bought anything from them, but I like the selection and prices. I can't say about India.