Many of the great punch manufacturers from 10 years ago are no longer around; although one can often find retired punches on eBay.
I think the most well known punches currently are EK (which includes Stampin' Up (SU) and Martha Stewart (MS)). I do own quite a few EK punches, but the bulk of my 700+ inventory consists of other manufacturers.
Due to having been collecing punches for over 15 years many of the punches I love to play with are made by companies that are no longer around. I've always stuck to more basic shapes rather than very specific images (IE characters such as people, witches, small animals etc). I find generally the more basic the shape, the more design possibilities ther are.
My ever growing collection consists mostly of the following:
Punch Bunch (PB)
Marvy Uchida (MU)
Unfortunately Nankong, Emagination and Family Treasures do not exist anymore. A few of their popular punch shapes were however picked up by PB.
For the best selection of basic shapes PB is your choice. It's incredible what one can make from a few basic shapes.
Take a look at their website for all they currently offer:
It's well worth the look at over 1000 punches to choose from.