What you want with a pair of shears is a strong, simple action that doesn't interfere with the job: whether you're using them as hedge shears, topiary shears or something more sinister.
The simple answer, if you needed to ask, is the Niwaki Garden Shears: they're perfect for just about everything - great balance for detailed work, tough enough for thrashing away at a hedge and good quality steel that holds its edge well but is forgiving enough if treated unkindly. BUT, they're not very long. If reach is what you want, look at the 30" Okatsune Shears with the rubber cushioning. They give you extra reach, and more power. Great for hedges and large topiary.
If careful clipping is your game, have a look at the Niwaki Topiary Shears. The long, blue steel blades are finer quality and fantastic to use, but you mustn't use them for heavy duty work, as the steel is too brittle. Bit like taking the jag off-roading. Sharpen these with our Niwaki Stones and the edge you'll get is amazing.
Finally, the remarkable Tobisho Shears. Rather like Arsenal of late - sublime, on their day (box clipping in June) but laughable on a wet December evening away to Stoke (cutting back an overgrown Laurel hedge.) Nice length, great steel, heavenly balance. Not for everyone, obviously, but try them, and they could well be for you!
One more thing: keep them clean and keep them sharp.