So, this is what I use:

https://www.amazon.com/Rambler-Stackable-Insulated-Stainless-MagSlider/dp/B08VF8ZKW9/

It's a Yeti, it's expensive and it is small at 300ml. There's a larger 415ml one but it feels like drinking out of a bowl because it's sooo wide. Even with the lids, it's just and uncomfortable experience for a weird reason. In the summer when it's hot, I actually eat cereal from the larger one because I hate when my milk gets warm.

There are plenty of knock offs of the larger one Aldi in the US has a house brand, Crofton that sells for $6. Zak! Designs sells one for $10 (currently on sale for $6 at Target.) The one that looks the most promising is at Walmart. They have a house brand called Ozark Trail and their version sells for $8. Unfortunately, I didn't see it when I did a search on Walmart.ca.

The downside to all of them is that they don't fit in a lot of cupholders. The Yeti has a really nice lid that I can manage, it's easy peasy because it's magnetic. It seems like it would be leaky because it also doesn't thread closed and it's just a magnetic slider but I once somehow managed to turn it over to set it down in the night and nothing leaked for the hours it was upside down. This is hands down why I choose the Yeti.

The word of caution I have for these other mugs are if they run through the dishwasher the paint tends to chip, crack or flake on the non Yeti cups. So if they offer, I'd try to get a stainless un colored version like the Yeti in the link.

If you manage to get a Yeti, you can feel good about getting colors. None of ours have flaked (my family gets discounted Yeti stuff, we're spoiled) through hundreds and hundreds of dishwasher cycles on extra hot and long with added detergent boosters.

Contigo and Hydroflask are other brands that have similar full handle mugs.

Buying in store is usually cheaper than Amazon (in the US anyway.)

If plastic is a necessity Tervis has a 500ml and a 750ml mug. Lids can be purchased with the mug or separately. They can be clear or highly decorated. Tervis is what I used before I found Yeti. The downside is that they can crack at the lip and lose their insulation. The cracking can happen with a hard fall or from using a refrigerator water dispenser (constantly pressing against the thing in the door, does it have a name? lol)

Another option is to Google, "insulated hospital mug". To find plastic options but most I've seen are liter sized.