obviously i have used all the platforms there are and i would rate amibroker #1 and multicharts #2 all others are lacking if you want to do your own thing and not settle for canned crap.
there are simply too many nuances for me to list them all just take 30 years to figure it all out like i did. i know this for a fact the largest funds in the world use amibroker because it will allow you to do whatever you wish to do. making money requires out of the box thinking, so don't buy a box.
speed - the load of complex calculations you can throw at amibroker is daunting, so i really like it. but i will say that it also has a learning curve since most users are very guarded with coding projects. it's mainly a boutique software with heavy participation of the owner author of the software and it has stayed that way since the beginning. not a bad thing.