Nothing wrong with a 2nd user machine, the biggest downsides probably being feeders as many people stick with a manufacturer and keep the good ones when they upgrade and the fact finance is much harder to get against older capital equipment. On paper these things are written off the balance sheet pretty quickly. However if going 2nd user I wouldn't go too old or too cheap, talk to some of the people selling new machines they might have something PX or perhaps might have something they will give you if you buy new feeders (this was a serious option I was given by MyData several years ago). If you choose something from the last 10 years you should be able to find something pretty capable, Yamaha/IPulse, Juki, Europlacer, Samsung,Universal & Mirae should all have machines that suit you, Fuji, Assembleon & Siemens from that era might perhaps be more commonly regarded as higher volume machines, that could mean if you find some they have been worked very hard.
In the US there seem to be several largish companies handling equipment like this, they all come up on Google or Smtnet so I would look them up, have a chat see what they have how helpful they seem, etc. A 2nd user machine will need more assistance than a new one so proximity of them or an engineer also perhaps a factor.
New, I think there a clear hierarchy you can probably ascertain just by looking at the specs of whats out there. If we are ignoring Chinese machines, at the bottom we have the Polish Mechatronik (slow/basic), then DDM,TWM Quadra, Autotronik (Manncorp in the US), Evest (again Manncorp in the US a basic copycat really of similar looking machines just not as well finished), Essemtec (the cream of the mid/entry level I would say) after that you can take your pick from many machines with various pros and cons depending on what you are trying to build. Build up a list of your projects what parts they use, what tapes or trays they come in, how tall they are and depending on what that tells you some machines will be more tempting than others.
In 2012 we paid ~£100k GBP for an Essemtec Paraquda with a reasonable handful of CLM feeders, a similarly loaded MyData was more like £130k as was an iPulse, Europlacer came in slightly above that but now they have the IICO which probably changes things a little. I didn't get quotes for Samsung or Yamaha but I suspect they were much the same as the iPulse. Juki would have needed 2 machines just to fit the feeders as their basic machine is small and the feeders slot hungry in the larger sizes, if I hadn't needed that many feeders loaded at once the pricing was about the same.
If you don't want to run conveyored, I would suggest an Essemtec Fox/Paraquda is pretty much unbeatable in standalone config, however beyond a 5-6kcph real world placement speed standalone is a silly way to do things. However take a bit of polish off an Essemtec and you get the Autotronik machines which are quite a bit cheaper, I would suggest getting up close with both. In 2012 you could have added Dima to the list, I don't think they sold much if anything into the US, but they were quite a nice machine and 20% cheaper than Essemtec, Nordson has killed of the p&p side of the business however which leaves question marks over 2nd user ones.
Important to remember tho' headline prices mean little here, like a car or a house you usually lease or finance these things so choose a repayment that works for you.