I think you mean Housesteads? ;-)
I have visited Housesteads and Vindolanda but not Birdoswald and did so independently so cannot really comment upon the day tour aspects.
However I much preferred Vindolanda over Housesteads simply because for me there was so much more to see. The museum has many more artifacts and on my second visit there about four years after the first they even had some of the Vindolanda tablets (letters) on display, although not the famous birthday letter to Sulpicia Lepidina from Claudia Severa, which is on display along with others at the British Museum in London. For me that was the deal maker. Those letters are fascinating. The tale of the water pipe was very amusing too.
Vindolanda and the Roman Army Museum nearby are run by the Vindolanda Trust and one ticket gained admission to both sites. Does the day tour allow you time to visit both?
I remember Housesteads as being quite a walk uphill to reach from the visitors centre, whereas at Vindolanda was much more easy on the legs. Also at certain times of the year you will see archaeologists and volunteers at Vindolanda which they are continuing to excavate and discovering new artifacts all the time. I don't know if anything similar is happening at Housesteads.