I'd recommend ignoring tube size. At the end of the day, you never buy a scope because you wanted it to be bigger (though you might pick one because you wanted it to be smaller). You get a bigger tube because it lets in more light, or has a greater adjustment range. N.B.!!! I said that's *why* you suffer with a bigger tube. I did not say that a bigger tube guarantees either of those things! And that's the rub. Don't lose sight of what you *really* want (clarity, adjustment range, robustness, adjustment accuracy, etc) Tube size is a side effect, not an attribute.
I like a 34mm tube right now, but not because it's 34mm, but because it's everything else...
GsT