I've now tried most of the alternative bars, and like them enough to persuade me to just order Exante shakes next time, although I do enjoy the Exante bars too.
I would rate them like this:
1. Tesco (choc)
2. Exante (toffee)
3. Biggest Loser (mint fudge)
4. Asda (choc)
The Tesco one I had this morning was the best so far - chocolately, chewy and very satisfying, with a decent aftertaste.
I like the Exante ones, but the toffee/raisin one is nicer than the choc/orange one for me.
I tried the BL mint fudge one last night - it was quite dry and the minty taste was a bit much. It felt like a chore eating it, but the amazing thing was that it was so filling! I had to leave a bit until later. Not the tastiest, but by far the most satisfying and useful, so I've ordered more of these to keep the hunger at bay
Asda - this was the first bar I tried and I liked it at first, but then it got a bit boring - dry, powdery and with a bitter aftertaste. Not totally unpleasant, but not as good as the Tesco equivalent.