Currently eyeing on few xiaomi vacuum robots STYTJ02YM, SDJQR03RR, STYTJ02ZHM, MJSTS1 but not sure which model is best to buy, any sifu recommendation?

Below 2k should be fine.
1c only has 2400mah battery capacity so not in my list

Where got orang kaya, installment only
Does 1c comes with anti-drop sensor?

Updates:
After few surveys finally decide to go with xiaomi 1t model STYTJ02HZM (aka xiaomi mop 2 pro+), due to bigger battery capacity and multiple maps support

Satisfied with its suction and battery, able to do vacuum and mop for an 50m2 area (total 100m2) and still have 1/3 battery left after that. Usually just set the suction at silent/standard level is enough to clean my house, rarely use strong/turbo since I don't have carpet. Rarely collide with wall or furniture also.

For mop function don't expect it will do a perfect job if there's dry stains on your floor, will need to clean self manually. Another thing is that I might made a mistake about saying this model has multiple maps function. So far I did 2 full vacuum on same area and able to perform room edit & virtual wall function but it doesn't show "save map" or "map list" option, not sure if it need to do few more runs, will update if it make changes later.

Just want to share with you all the solution I used to fix clogged water tank due to use of disinfectant/detergent.

I figured out my tank is clogged and notice that it might because the tank motor is not powerful enough (when running with robot) to push the blockage out from the hole, so I fill up the tank with some clean water first and then get a 12V dc battery and manual connect to water tank using a cable, obviously the motor is running better and manage to release water again. Repeat to run the tank motor until you feel the blockage has been cleared.

Tested the mop function and it's working again, save money from buying a new water tank