Sorry for the super late reply. I live in neither. However I live opposite the Tannery in sentinel towers, and have a friend in the Tannery.
Tannery
Pros:
-Huggggeeee kitchens like oh my gosh
-Considerably cheaper than CV
-About 15 minutes walk to the business school and the edge sports centre, about 30 minutes to the Michael Sadler building (languages mainly) though a frequent bus runs from RIGHT outside to the parkinson building for only £1 each way
-Near an Aldi? Not really the best pro
-Next door to the fire station, depending on where you get put in the building can 'look at fit fire men'
Cons:
-Rooms aren't that great, they're decent but nothing fantastic
-It is all uphill to university.
-It's not 'on campus'
-Whilst there is a common room I have never ever seen it used
CV
Pros
-On campus
-Supposedly very nice rooms
-Party central (this would be a con for me but there we go)
-Very close to Morrison's to go shopping
Cons:
-Oversubscribed every year. If you make this your choice you have to accept. it's possible you won't actually get to live here and may be placed elsewhere
-Very very expensive.
Guess it depends on what you specifically want
I love Sentinel Towers to be honest, but it's a 'quiet' accommodation (I say this like that because every weekend there are parties)