Just check you can do the kind of sessions you want to do on the rollers; some will not give you the resistance you need to do workouts at tempo and above.
Some people find that the added interest of having to balance helps them do better/longer/harder sessions.
Other people find that they prefer a turbo where you can focus purely on physical effort.
In an ideal world you would have access to both as they are different tools, but if you can only have one and need to be fit for next year I'd get a turbo.
Discuss light weight issues concerning road bikes & parts.