Vandersteen 2/3 vs. 3A MM de Capo vs. GMA Europa

I would like to upgrade my modest system:

Squeezebox (stock) playing FLAC files
Rogue Audio 66 Magnum
Threshold S/200
Onix Reference 1 monitors
ACI Force XL subwoofer

I have a large room, about 14' x 28' (somewhat irregular shape) that is open to another room and a corridor.

I think that speakers would be the best upgrade at this time and the three I have mentioned in the title are high on my list (I haven't heard any of them so it is based on what I read here). I’m interested in other suggestions. The budget is $1500- $2000 used, depending on whether I need to keep the subwoofer.

I often listen to music many hours a day so non fatiguing sound is important. Also I don't always listen from the sweet spot and I would like speakers that sound as good as possible throughout the room. I often listen at night at lower volume. I listen to all kinds of music; almost everything except orchestral and hip-hop/rap .

I’m new to this hobby and I’m not sure I know exactly how to describe what I’m looking for. I want a more room filling sound and for the speakers to disappear (that is sometimes a shortcoming of my current system). I like details and good imaging.

I should mention that one of the reasons I’m considering 3A MM de Capo is because I might want to try a tube amp in the future so higher sensitivity speakers would be useful.

Am I on the right path thinking about the speakers or should I consider changing the electronics? I would appreciate any specific suggestions but also general advice how I should go about the upgrade.

Thanks,
Adam