Shorts and longs let you use unrealised profit as margin which very few companies allow you to do and which is a very, very powerful weapon for the trader. Also, all stops are guaranteed which is good - particularly as it means margin requirement is minimal. Nice simple platform and excellent execution. Major downside is no order entry system. Limited markets (e.g. no cash FX) They also have no charting or news etc
IG were OK. However, they didn't have some of the markets I wanted (e.g. US 10 year and Wheat) plus I hate the fact that you have to define your stop in number of pips / ticks rather than a specific price when you first place your order.
VDM Spreads have got some good account features (e.g. they chart your P&L equity curve) and have tight spreads and a good choice of markets. Little features were impressive (such as the automatic conversion of your stake size into contract/cash equivalent - somewhat useless as far as I'm concerned but interesting) They have a good order entry system too. Major disadvantage for me was the slippage I got on almost every trade at even very low stakes (e.g. £1 a point) in markets that you would not expect slippage on. (e.g the Bund). Slippage ranged from 1-2 pips/ticks on most trades down to 33 pips on one. (it was news but I absolutely know they could have got me out faster). Also, had a stop disappear once. Alarming stuff. However, good customer service in their defence.
ETX were good. Didn't have any problems with them at all.
Finspreads were pretty bad. Slow execution. Orders disappeared a couple of times. Their charts work off the mid-price which annoys me greatly. Margin requirements are very high.
Just testing CMC now. I already have a major problem with them in that they won't let you place orders near to the market. (e.g. several full points away in Corn which I find ridiculous) I really like their platform though. It's the most professional looking one I have used.
Also testing Tradefair. Looks and feels like E*Trade (Capital Spreads). Love it so far.