i personally use amibroker and have very less frequently used NT. But the facts quoted by mt4 are correct that NT is moe suitable for complex strategies and amibroker sometimes feel lacking some important aspects. You code some strategies where x axis is not time and is some other variable amibroker will not be able to handle that. In amibroker x-axis is time, y can be anything else eg. volume, price, averages etc but x-axis is time that is the biggest bottleneck of ami.
If you have not come across some complex strategy where ami failed to do the job then you really cant comment on it.
One simple example can some one draw equivolume charts on amibroker ?
Code:
http://stockcharts.com/school/doku.php?id=chart_school:chart_analysis:equivolume
http://www.traderji.com/amibroker/18446-can-we-draw-equivolume-chart-amibroker.html