I use an ISCO companion and Rf constantly. They seem simpler and more reliable than Biotage in my experience, but some people love Biotage. I have also used a few other systems, but in the US, it is mostly ISCO and Biotage now. The prepacked columns are very helpful, and I can purify up to 8-10 compounds in an 8 hour day easily. The standard systems work really well from a 4 g up to a 40 g column, work ok for larger ones up to 300 g, above that, you can get good results, but sometimes a manual column is cheaper and easier, or at least get a rack with bigger tubes. But for 10 mg to 5 g samples, the ISCO does well. There columns are better designed than Biotage also, the ISCO compatible columns from Silicycle are quite good also.
As for used systems, you may find that if you buy a couple of unknown used ones, you can build a good one, but it depends how handy you are. They sell working for $10K and up, so buying 2 unknown ones might not be that bad, but I would try to find a working one. There are plenty at lab auction sites coming up for sale soon.