[Overkill]

There are many different models of machines, and a variety of opinions on which is the best. To truly give an opinion, knowing what you are trying to do with it would be needed.

The machines were sized based on their shearing ability. But most people here don't use that capability much, they are usually used for sheet metal forming operations.

Basically - there are the smaller machines which will form automotive thicknesses of sheet metal. And being smaller, they can be put on casters, operated with 110V on a VFD, etc. Most use 5/8" tooling.

The medium sized machines - P5, P6, are a little large for casters and will take up a fair amount of room. Their throat heights are the same as the smaller machines, and if doing a deep dish form, the throat height can become an issue. Most use 3/4" tooling which seems to be the most common.

Large machines - P7, P9 - can get massive and many shops don't have the room. They use 7/8 and 1" tooling.

One of the most desirable models is the P21 - it has a taller throat height. And there are a number of desirable options - air lifter and duplicator attachment. It uses 3/4" tooling.

Before someone corrects me - all the tooling is metric, not SAE. Also, I'm not covering every machine, just some examples.

One important thing to look at is the input power - there's some odd balls out there.

The rarest of machines, that has more throat height, are the Trimmer models. Rare = expensive.

Before you invest, go to one of the metal shaping work shops - even if you have to travel - and use one. They can do a lot of interesting things, but are not the be all and end all.

One thing they are not is a hammer. Try using one as a hammer and be prepared for a repair bill.