I went with a 3.4 for the added power over the 3rz. I am in the middle of replacing my tired old 22re with a 3.4 right now.
The 1 thing I will say is find a complete vehicle and pull everything you might need. It is the little thing down the road that will start do drive you crazy and possibly start to strain the bank. As far as fuel economy, I never got the best mileage with my 22re so I doubt I'll complain about the new v6 consuming fuel.
