Depends on what you build, although most kits released nowadays by Tamiya, Hasegawa, Revell Germany, Dragon, Trumpeter and a few more can be considered safe purchases. However, there are exceptions as mold swapping abound between manufacturers and I'm not necessarily talking about brand new molds here!
If you build small scale AFVs, you'll probably prefer another set of manufacturers than if you're building larger scale AFVs. Possibly the same applies for aircraft and civilian vehicles.
At the end of the day, it also depends on exactly what you want to build. F-14s and Panthers are plentiful, but if you want a DFW T-28 of WWI fame or a Dassault Rafale, there's not as much choice around...