This is without a doubt my most versatile light modifier and it gets used all the time. The combination of a soft light source (when used as a shoot through) and various reflectors (with the different covers – not shown in the picture) makes it extremely useful. It’s also very easy to pack and bring with you – the one I have is the 75 cm version, which is the bigger of the two available.
If you usually have access to a willing assistant, then this is a no brainer, it might even be all you need on a lot of occasions. It does cost a bit but if you’re only getting one reflector, make it this one and you won’t regret it.