The Barbara Bush of the air force

"The MiG-21, despite being the Barbara Bush of the air force, is still much cheaper, simpler and easier to maintain than the more complicated and expensive MiG-23 and MiG-29. There's still a large number of MiG-21 operators vs 23 and 29 operators and parts are easier to find. Plus there's ALOT of companies offering upgrades to the MiG-21.. thus it makes a cost effective interim solution until something better could be acquired. It is likely that this 'better' aircraft will be western, so why not upgrade it with western avionics and get the pilots used to them beforehand."
(Dec. 27, 2004, Key Publishing Ltd. Aviation Forums)