It's odd that you would say two seasons as personally I think Ronaldo's best season for us was actually 2006/07 - that was the most rounded he has been as a player. While his goal output increased in subsequent seasons, it definitely did so at the expense of other areas of his game. (Despite 2007/08 being Ronaldo's WPOTY season, I think Ferdinand was actually our best player that year).
The Bale of 2012/2013 is a very similar player to Ronaldo's last two seasons with us though, and that would make sense - Bale seems to have modelled his game on Ronaldo's. Of course, Ronaldo was our player so there's an inevitable allegiance to him even now, but putting this aside, as footballers, I don't think the difference between them is anything like "a long way ahead". There's facets of Ronaldo's game that are better than Bale's and vice versa.
Yet despite what I consider similar ability as footballers, I think the mooted sum for Bale is too high. Regardless of its relevance, Ronaldo's achievements were obviously a selling point and contributed to his price, as did his (already high) marketing profile. It can also be presumed that prising a player away from United is/should be harder than Tottenham (though with Daniel Levy in charge, you could argue it's harder to prise a player away from Tottenham than any other club in the world!)
