I have had a Weider 9930:
for about 8 years. Granted I haven't used it nearly as much as I'd like to, but that's my problem.
A few of my complaints about mine are the cables stretch over time, so you'll need to adjust them. With the cables and all of the pulleys, there is a bit of a "lag" from when you start a lift until the cable is tight enough to start to lift the weight. It's not terribly noticeable if your cables are set properly, but it is there. This may have been remedied in the newer models. With the 4950, just make sure you have enough square footage in the room.
As for the Boxflex, I've never used one so I can't say.
All in all, I'm pretty happy with my $300 purchase all those years ago. It's made it through 2 moves and years of use and looks like it'll be around for a while still.