Hi Gary
I guess it comes down to how many parts per PCB you want to place.
Vision is almost 'standard' for all the small machines now.
All machines are capable of good accuracy if set up well.
The difference comes down to the type of feeder.
The "built in" tape feeders are cost effective, but you need to intervene more often.
The cartridge feeders like Yamaha CL in the QiHe TVM920 or Charmhigh 930 are the pro feeders, they are reliable over thousands of parts. but you got to fork out $60 per 8mm tape feeder.
All the machines will do pretty good loose parts and tray pickup.
Something like a TVM802A or 802B are quite cost effective machines, but the simple feeders need more intervention - but that may not be an issue on small numbers of placements.
So, when you jump to the bigger machines, you also need to buy feeders.
something like this : (price including cartridge feeders)
TVM802B : 4k (built in feeders)
Neoden4 : 6.5k (built in feeders)
Charmhigh930P4 : ~ 9k with yamaha feeders
Qihe TVM920 (bigger) ~ 10k with Yamaha feeders
As for software, the software with the Chinese machines is satisfactory at best. But certainly usable. OpenPNP support is being added to these machines.
regards