Binoculars are about magnification – no question about that. But it’s more complicated than this. Higher magnification (power) comes at a price: The higher the power, the more difficult to handle the instrument, to such an extent that binoculars with magnification of more than 12x are useless unless used with some sort of stabilization like a window mount or tripod (read my Binocular accessories). Higher magnification also has an impact on other features of the binocular. You can read more about this at “Understanding binoculars 2.”
A magnification of 8x is an excellent choice. More powerful than this and you could end up struggling to get a good image. If you really have a steady hand, you could consider 10x, but read “Understanding binoculars 2” before buying.
Another option would be to go for a type of binocular known as an image stabilizing binocular. Just follow this link for a discussion of this category of binoculars.
Finally, you do get binoculars with variable magnification, known as “zoom binoculars“, like the Pentax 62217 UCF II 8-16×21 Zoom Binocular. In spite of certain problems associated with the zoom function, these binoculars are quite popular. You do get a few where the manufacturers seem to have sorted out the problems, but these are more expensive. An excellent example is the Alpen Apex 8-16 x 42 Zoom Waterproof Roof Prism Binocular.