Lille or Paris for a day by Eurostar with DC

[ErnestHeminsway]

My DS has a birthday soon, he's asked to go to France. He's never been abroad but I have got our passports done.
We could go from Ashford International.
If anyone has experience of Paris/Lille in a day with DC which one would you recommend? Lille is only an hour and train times better. The price is the same.
Thank you in advance.

I'd probably go for Lille then because it will give him a flavour of France and the small historic centre is walkable so you won't waste time traveling. Paris is way more glamorous and exciting but for a day trip you probably wouldn't have time to do e.g. Eiffel Tower or Notre Dame (long queues). You would have time to do a boat trip on the Seine though, which is a good way of seeing lots of famous stuff, if he's interested in history. If not, maybe stick to Lille and frites/patisserie/chocolates.

I have done both. How old is he?

My parents took us on day trips to Paris in our teens. They were enormously exciting, wonderful days which I remember vividly. We used to go to the Terminus Nord brasserie opposite the Gare du Nord for dinner, and tell them the time of the check in. Once when I was in Paris on my own for the day I sort of half dozed off at the end of my dinner and they woke me up so I could get there in time!

I did a day trip with my Dad when I was 23. We went up the eiffel tower and to Au bon marche. I bought DH a bottle of sauternes there and gave it to him on our wedding day. We drank it on NYE just gone.

So many happy memories. Lille is nice. But it's not Paris.

Thanks justanother and callmecordelia, you've both echoed my thoughts. I've been to Paris once, very briefly, so I don't know it at all. I think, for a day trip, it might be too overwhelming for both of us.
DS will be 11. I think Lille will be more manageable and less busy? justanother is it feasible to just wonder around from the station in Lille? Is there anywhere in particular that we should go/avoid. Frittes/patisserie and chocolate will be a winner!