Hi Rahul,
You have a lot of options for doing Mbbs abroad.Many countries require you to learn there local language.
Some countries also require a previous UG degree.
The duration of the course is also different everywhere.Keeping all this in mind you need to decide.
USA offers excellent training opportunity renowned worldwide.As far as cost is concerned there are many factors that need to be considered.Starting from the tution and hostel fee, learning of local language, cost of living , value of currency of that region, no. Of times a year you would like to come to visit India .
Having said that , USA , Canada and UK are costlier than  Russia, China , Bangladesh.
For more details click on the link below
https://studyabroad.careers360.com/articles/medical-studies-abroad-top-10-countries-study-mbbs-abroad
Hope this helps

According to my view Russia is best country.