Tum tum usually. Or just cheap generic supermarket straw bottles, we’ve got a few different ones and they all do the job.
Tum Tum x
Very happy with these https://www.ebay.co.uk/itm/124285625914?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=psc3U34pToW&sssrc=4429486&ssuid=wtk_8rrFRxG&var=427726648524&widget_ver=artemis&media=COPY
Tum Tum straw beaker x
Tumtum but I’m not sure they’re worth the money. He took to them easy but they’re Hard to get in all the crevices for cleaning. Eventually starts to leak. I’ll get generic if I ever need to get more.
We use a sippy cup from a brand called Oberni and it's working really well for us. It's a straw cup and has a little sliding lid which stays attached but also closes it sealed. It has the side handles and a strap for around baby's neck(mine absolutely hates the strap but maybe other babies don't mind 😅). The capacity is 270ml so pretty good for out and about 😊