[In Omnibus]

vBulletin 4 and vBulletin 5 are like apples and oranges. While they serve the same basic principle of being a message board forum that's where the similarities end.

It really depends on what you want to do with your site. If add ons are your thing you may want to go with 4, as it has far more add ons that serve far more purposes.

If customization is your thing then 5 allows virtutally 100% customization of every page. There are a handful of add ons for 5 but not nearly as many as for 4.

The themes / styles for each are also very different.

Before we even discuss add ons let's talk about what you want to do with your forums.

You can always upgrade from 4 to 5 but you will lose any add ons from 4 as they are incompatible with 5. What is far more difficult is going back to 4 from 5 since that requires a backup of the database and the 4 files.

I've had great success with both versions but for different reasons. In my opinion 5 looks far more professional out of the box. 4 looks far more entertaining out of the box. But with time and patience (or with money) either version can be made to look exactly as you want.

So, again, it reverts to what you want to do with your forums. Are there add ons you actually need to operate your forums? Or are they less functional and more bells and whistles?

Give us some idea of what's important to your forums and we can give you a better idea of which version best suits your needs.