I loved long-haul, loved the majestic A330, and loved the days away down-route. But I think it is mostly 24hr bullets now?, so no fun anymore.
I personally would not move to the ME - you hear too many stories of airlines falsifying log books, a brutal operational culture, limited lifestyle in very hot countries, and extreme long-haul operations.
When the sh*t hits the fan, a Captain can be employed elsewhere as a Captain or an F/O. An F/O can only be employed as an F/O.
If the command course is on a useful jet and is a reasonable certainty - i.e. you have already been told you qualify to be on the next B737/A320 course - then I would go for the command. Glamorous long-haul probably doesn't exist any more?