Hi,
I'm assuming by 'less international' you mean single-office firms who use a best friends model (ie Slaughters/ Macfarlanes/ Travers)?
First of all, I would consider your framing of the response quite carefully. These firms aren't any less international in the work they carry out, they just take a different approach to multi-jurisdictional work.
In terms of responding to the 'If you've applied to X, why apply to us?' question, I think a combination of pragmatism and acknowledging that both firms have benefits on the international standpoint, but also finding alternative parallels (eg if both firms have a strong PE/ Litigation/ M&A practice, focus on that). The other thing that I always said- which I don't think there's any shame in saying- is that, at the end of the day, you have to be pragmatic and, in an exceptionally competitive industry where you're competing with some of the strongest graduates in the world at any given time, that means making a variety of applications to a variety of types of firms.
In terms of responding to a 'what do you think of our international strategy', I would personally just break down the benefits to the best-friends model and then resolve these to why you feel you could actually benefit from them. I would encourage you to think about international risk exposure and ensuring the absolute best quality of international work here. Another reason I usually added was that, for various reasons, an international secondment isn't an opportunity which I find in the least bit appealing. When I spent time with several firms with loads of international offices, I felt there was actually a lot of pressure to go on a secondment, even as far as a negative perception of you if you didn't go on one. Working from single-office firm is much more appealing in that light.
Hope this helps 