My house is comfortable to live in.

[tufguy]

What we should say "My house is comfortable to live "in" or "at"?

Please check.

 

[emsr2d2]

What we should say "My house is comfortable to live "in" or "at"?

Please check.

Look at the word order at the start of your question.

 

[tufguy]

What should we say "My house is comfortable to live "in" or "at"?

 

[emsr2d2]

Now remove the first word and capitalise the second.

 

[tufguy]

Should we say "My house is comfortable to live "in" or "at"?

 

[emsr2d2]

Now your question is correct. If you feel you must use the last part, use "in". However, it's somewhat redundant. "My house is comfortable" would suffice.

 

[GoesStation]

Should we say 'My house is comfortable to live "in" or "at"'?

Ems's approbation notwithstanding, I still have a quibble with your punctuation. When you nest quotations, you have to alternate the style of quotation marks. You also omitted t final closing quotation mark. See my corrections above.