Caroline,
Both premium products are similar to be honest. FCA's SCP cabin probably has the edge, but only just in my opinion. Seat pitches are 36" in SCP compared to MYT's 35" (whats an inch!) and FCA's seat back IFE have slightly larger screens. Saying that, MYT have the external flight cameras so its swings and rounabaouts really (assuming they assign an Airbus A330-243 rather than their Boeing 767-31K's). Both are very good. My Travel are an excellent airline in my opinion. I've travelled with them quite a lot and once had a 52 hour delay with them in Jamaica when their DC10-30 went tech on us back in 2003 (now they were a proper airliner!). They were very professional and I'd have no hessitation in recommending them. FCA probably have the edge in terms of cabin interiors, but I prefer the Airbus A330-243 as an aircraft becasue its generally smoother and quieter than the Boeing (plus the A332's have British built wings and the mighty Rolls Royce Trent 700's powering them!).
If you were flying in economy, then I'd say go with FCA because you can't beat star class, but since you are wanting to upgrade, if the price is better with Direct, then I'd go with them.
Hope you have a grreat time,
Darren