J-Trader is probably the industry standard.
As old as the hills, but still the most widely used platform out there. Very simple to use, but no bells or flash gizzmo's
Some broker provisions can be dodgy if they dont put the infrastructure ($$) in place. Man have and do, as do other big names.
X-Trader is the other alternative. Hard to learn, starting to get unreliable, bad support, expensive. Super fast, but that speed is a waste of money paying for now due to the black box engines out there.
All other platforms will be 2 dime alternatives that are unproven by 1000's of traders the world over. Unknown reliability, unknown people behind them, unknown user base etc.