There is a marked difference between the 2.5 and 3.0l engines (about 40kw??? I don't recall exactly), and - at least in our market - significant difference in features. But there is not much point going the 3.5l V8 over the 3.0l I6. Dad owned a pre-facelift E39 535i and once the updated 3.0l engine was introduced (early 2000's), there was about 10kw difference between the engines and the 535i became virtually irrelevant. That said, it did offer the nice V8 torque and a few extra features, but for the price difference it wasn't really worth it.

The 3.0l of course also offered better fuel economy and efficiency, as the 3.5l engine wasn't updated through the E39's lifespan (as far as I know!), and was quite an old engine by the time the E60 came along.

I would pick the 530i out of the three - a great balance of performance, economy and value. Still a good looking car too.

Also - I am not familiar with the 'exclusive' edition, BMW only ever sold the Executive and Sport models here (of which I would pick the executive - I think the sports pack is starting to look a little tacky nowadays, especially those 17" M wheels). The 'exclusive' pack sounds like some sort of limited edition (with a few extras added?), in which case if you were to find one with low miles, in good condition and for the right price I'm sure it would serve your wants perfectly