best suits vs suits best

Question

I am developing an app and I have this sentence in one of the screens:

Select the area that best suits your ad

but one of my team said it is not correct and it should be like this:

Select the area that suits best your ad

I believe that both works, but I want to know which is better and why

Note: there is a bet on this

Answer 1

In normal conversation, I'd probably say

Select the area that suits your ad best 

But that ends on 'best' which is sometimes considered informal, and so

Select the area that best suits your ad

would be used in more formal settings.

Select the area that suits best your ad

Is a rather odd order, at least to my UK ear. It also is ambiguous, 'best' here can be read as a verb and 'suits' as a plural noun, so this means 'select the area where formal clothing defeats your ad'.

Answer 2

The sentence

Select the area that suits best your ad.

is grammatical, but it is not recommended to separate the verb from its object:

Keep the subject, verb, and object close together. The natural word order of an English sentence is subject-verb-object. This is how you first learned to write sentences, and it’s still the best way. When you put modifiers, phrases, or clauses between two or all three of these essential parts, you make it harder for the user to understand you. (plainlanguage.gov)

Either

Select the area that best suits your ad.

or

Select the area that suits your ad best.

are acceptable, but the first option is the most common:

Note that GNgram did not find any instance of that suits best your.