Although have both LUG and CODA, the only system I've ever used was FASA. As a system, FASA has an excellent chargen system that virtually writes the PC's background for you. However, in today's terms, the system is horribly dated. There is no character customization of advantages and disadvantages, which makes for bland characters. The tactical combat system of Action Points is an extremely clunky mechanic, but crunchy was how things were done in that game design era, so it's not out of place. Many givens in game design are absent in FASA, there isn't a real Initiative system, just highest DEX goes first, no random element involved. There isn't a Notice/Spot Hidden/Sensory skill or mechanic of any kind. Character advancement is very limited and takes a long time to gain a level of competency or diversity as you see in the series.
Yet, despite these flaws, I still like and use the system, albeit with some house rules to cover the most glaring gaps like initiative and noticing things. I have tinkered with, but yet to settle on an advantages/disadvantages system or a replacement for the Action Points mechanic, but I continue to tinker and figure I will get there one day.
"For to win 100 victories in 100 battles is not the acme of skill. To subdue the enemy without fighting is the acme of skill." Sun Tzu - The Art of War