Because the games aren't linked through storyline maybe picking by choosing a setting you like would be a good place to start. 
VII is futuristic with steam punk vibe
VIII is futuristic
IX is medieval style (also Steiner is just a lovable idiot
)
XIII is also futuristic but as most people have mentioned here, best probably to start with the most noteworthy 3
	
		
			
		
		
	
				
			VII is futuristic with steam punk vibe
VIII is futuristic
IX is medieval style (also Steiner is just a lovable idiot
)XIII is also futuristic but as most people have mentioned here, best probably to start with the most noteworthy 3
	
 
 now its just pumping out the same old open world crap