We will be traveling from London to Paris (my H, d and I)for a few days and I was wondering, convenience-wise, would it be easier for us each to bring a carryon or for one of us to carry a regular size piece of luggage with all of our things?

Two carry-ons would be easier to manage in luggage racks though there is plenty of room to carry on a large suitcases or more too. Eurostar also has a checked baggage offer if you don't want to hassle with bags - have not checked recently but always used to have for about $20 or so per bag.

Depends what you define as "regular", but in principle, two smaller bags would be easier to get on and off the luggage racks (and might even fit in the racks over your seat rather than at the end of the carriage).

Mind you, some people do bring on and manhandle much bigger cases than I'd be willing to deal with - but they can be an irritation to other passengers.

I prefer, when traveling with my husband, to bring two smaller cases, and to split our things among the two. For example, I put everything we both need the first night in one case so we don't have to do much unpacking until the next morning. I also keep all the shoes, umbrellas, extra outerwear, and other bulky items, in one case, and I stuff socks and underwear around the bulky items. As the trip goes on, all the dirty laundry also goes in a single case. This also allows me to pack everything very flat in the non-bulky-item case.

Two carryons would fit better in the luggage rack

Sometimes a first class Eurostar ticket at a discounted price may not be much more than a Standard class one and IME of first class there are always empty seats and lots of room to put bags near where you sit - no shoving into maybe crowded racks. check first class too when checking fares - if not much more go for it - the complimentary meal with unlimited booze or drinks is worth a pretty euro too.

If you are in the same carriage with other heavy packers, they can manage to use up all the luggage rack space before you have a chance. In this case, you have to keep your luggage around your seat. Between back to back seats in the open seating section, there are usually triangular spaces you can store luggage. One 26" might fit in this space. When I end up sharing a carriage with escorted tour groups, they would also fill up such spaces between the seat backs. The only space left to us would be the overhead racks because the heavy packers cannot use such spaces.

Looks as if there are three of you, your daughter also, correct? Then three bags. Each of you carry your own stuff. The bigger the suitcase, the harder it is to get up the steps, down the isle and up on the racks.

Thank you all- it is as i thought it might be. Three small bags it is! Thank you.
PS- the first class ticket was about 3 times the price, so we opted for table seating in regular seating. We will want to dine in Paris so the food wasn't a carrot for us. It would have been nice to travel first class but i don't think necessary for this part of our trip.Thank you all!

BTW, first class on Eurostar is hardly ever worth the price. It is only a 2 hour trip anyway. I often opt for first class in Europe and the UK if traveling more than 3 hours, but never if travel time is under that. As you said, it's simply not necessary.

But it is not unusual that a discounted first class ticket is not much more than the cheapest standard-class ticket available. Definitely not necessary on any European train but IME the Chunnel trains there is more of a difference between the classes than typical Continental trains - in part because the train cars are more narrow or were but newer ones are not I think.

I've always seen several empty seats in first class and in standard class often all full and being tall my knees inevitably stick into the seat back - that is if I don't get an aisle seat.

Not necessary but if the price is not that much more as it can be well worth the difference then.

and for 3 times the price definitely not worth it for the average traveler for a two hour trip.

I wish there was a way to "Like" replies. Thanks everyone!!