If you're not trading thru an ECN broker like Interactive Brokers, MB Trading, Dukascopy, etc, then you're better off trading FX futures.
Alot of other fx spot brokers interfere with your order execution so it'll be difficult at times to make a profit on a trade.
The downside to fx futures is the lower leverage available to you. Plus with fx futures you typically have to open an acct with no less than $2000.00-$5000.00
With FX spot broker like MB Trading, for example, you get the benefits of no order interference from your broker, very good spreads, and up to 100:1 leverage. Interactive Brokers is very good too, 50:1 max levg I believe.
Note: the new financial regulation bill is capping max retail fx spot leverage at 75:1 from what i was told by an industry insider with connections to the CFTC. Will take effect next year If I'm not mistaken.