Amibroker has everything you could possibly want. The code is VERY similar to Metastock, you can also quickly convert metstock code to ami code. It has all the standard indicators built in plus you program in whatever else you want or download from the net.
I have a fairly large database and she still rips along, never had any problem with the speed and my PC is several years old.
I believe you can also use ami with tradesim though I have never done it so can't really comment.
For the substantial price difference, I can't really see what MS offers that is so much better. Having said that, I haven't personally used MS so maybe someone who has used both can comment?
Cheers
AV