Whilst both venus are accessible with adequate disabled facilities and seating spots for those with disabilities I would have to favour the 3Arena for a number of reasons.
Firstly the underground parking with close proximity wheelchair access that makes transferring in wet weather less challenging.
Secondly the elevator facilities throughout the building make for ease of movement between floors.
The wheelchair seating in the 3Arena is far less invasive than in Croke Parke. In Crogh Parke all wheelchair users are bunched together on a stand at the complete back of the Parke whilst in the 3Arena the wheelchair seating is far less segregating and intrusive dispersed among the regular seating with freedom to go to toilets\bar as you please.
The view is far better and less restricted from the seating facilities provided for wheelchair user inthe 3Arena compared to other.