Well if you want to be a smartass then how about trying a demo of Civ 4 and comparing it to the demo you played of Revolution

Or follow my advice and go with the cheaper one (Civ 4 Gold Edition that also has the expansions is $39.99) since it is always better spending less on an introduction to a series than paying more. Or go the even cheaper route and rent Revolution to see if you like the full game as much as the demo. You could also ask on another forum since there are not exactly a ton of PC gamers here. Mostly console gamers if the number of topics about console gaming compared to the few that pop up about a PC game didn't make that obvious.
I have not played any games in the series but a strategy game like that is not very common on consoles for a reason and that is because a controller is not the ideal way to play them. Which is why I would have to guess the PC versions are better and also why the series has been 95% PC based. But based on reviews it sounds like they at least did a good console version unlike so many other strategy games that have been nothing but epic fails on consoles no matter how great they were on PC. So if the controls work it evens the playing field a lot more.
Also it seems like it has been a little more "casualized" with the more cartoon look it now has. The interface has very obviously been toned down with a much more streamlined way of doing things. This goes back to the whole controller thing. But more so OXM mentioned in their review that the average game of Revolution takes 4-8 hours compared to the days the average game in PC versions demanded. Seems to me like they shortened things up to make it a little more friendly to a non-hardcore gamer that is going to want to have these much longer games. So depending on which group you fall into that could be another factor.
Of course having not played it I can't say what the modding was like for sure but as any serious PC gamer knows modding can do stuff for a game that a console game won't experience. But based on a quick google search it seems like Civ 4 does have some good and popular mods such as Fall From Heaven 2.