First, Germanic and Slavic haplogroups/clades must be eliminated from the equation. I-Y3120 is Slavic and is not Dacian, it arrived with Bastarnae from Western Europe and all bar A2512 who likely descend from Bastarnae expedition in 2nd century BC, seem Slavic.
I-Y3120 is the single most common hg among Romanians, and I see they have been vocal about ludicrous notion of this hg being Dacian. However heavy Slavic influence is in agreement with onomastical and other evidence which indicates that there is no such thing as Vulgar-Latin/Romanian speaking population north of Danube prior to Vlach migrations of 12th-13th centuries, I do leave option for some groups being present prior to that but Daco-Romanian continuity is impossible to defend, it is ludicrous to think latinophone Romanian nation formed during the short Roman occupation of (part of) Dacia. Already it is clear nearly half of Basarabi surname carriers are recent Medieval migrants from the South. And such tendencies are easily observed in some other haplotypes as well.
I guess that is the real reason why Romanians don't get tested, at ftdna i know little over 100 Romanians, and most of the info has to be taken from studies, whose sample is for ethnic Romanians over 500 with different regions.
So Slavs, Germanics, recent Vlach migrants from the South and others have to go out of equation.
However there are those haplogroups or more precisely subclades that seem clearly present in Dacia in antiquity.
I see you aren't tested like most of these partisan internet warriors gidai.
Get tested before fantasizing about Dacians or anybody else. However Vlachs who arrived from the South seem pred. of Thracian ancestry so they have some distant relation to Dacians themselves.