In reading the Rick Steves book on Ireland 2019, I can't really see what would make me choose one bus company over the other. If you have used them or have an understanding of this, I'd love to hear your thoughts. Thanks.
We chose Red in May 2018, but I don't think it was based on any particular criteria. It took us almost everywhere we wanted to go (and on arrival day, we just settled in on the top level and rode all over to get our bearings.) The one exception was Kilmainham Gaol; in order to arrive in time for our reservations we took a taxi, not being comfortable with the Red HOHO schedule. We did ride it back into the town center after the Gaol tour (which we can recommend highly.)
I am also planning for a few days in Dublin this September. My thought is that if we decide to do a HOHO bus, we would pick the one that stops closest to our hotel.
We were not very happy with the Green Bus.
Why not happy with green bus tour?