Before I start, I will say thanks to Envoy, who had the original idea of making these VS. threads, awesome idea Envoy!
Latias and Latios have many things in common.
-They are both Legendaries.
-They have the same types.
-They have almost no differences in the moves they learn.
-They are Bother and Sister.
-They have similar appearances.
The only differences I can think of are.
Latias is a girl, Latios is a boy (The obvious difference)
Latias is smaller than Latios, and they have different coloring.
So which one do you like?
I know it is a tough one, but they have different designs, characteristics, ect.