Well... ok.
What I should make clear is that in terms of brands you have no "bad" options. The Mares Abyss is a good all-round regulator so I would personally lean toward using that one as a baseline to compare the others against in terms of how it dives and the price/performance indication. If I remember correctly, the Mares Abyss is the regulator Mark Ellyatt used on his back gas for his 313m dive so I would see that as proven credentials.
The Sherwood Maxiumus is also a good regulator and while the one I had doesn't compare in my mind (once again, I'm biased) to the Aqualung Titan in terms of price/performance, Sherwood does have a well deserved reputation for building highly reliable equipment.
I don't know much about the Scubapro line and I've never owned one but you seldom hear people complaining about them (aside from some older models that were prone to IP creep). I'm sure the scubapro dealer can offer you an option in the same price class as the Abyss and Maximus so I would certainly consider it based upon brand reputation.
In terms of budget I would also suggest setting the bandwidth based on the Abyss/Maxiumus. Don't forget, a regulator is (should be) a long term investment so it's really worth investing in one with good performance right from the start.
Whatever you do, don't just buy one based on the specs on paper. This is the kind of thing you should "test drive". Regardless of the specs they'll all "feel" different under water, so make sure the shops offer you the opportunity to try them out, even if it's just in the pool.
Good luck.
R..
