In my opinion yes, the 328i is the one to go for if you buy a July 2000 or older model, the 330i if you buy one newer than that. The 320i, 323i and 325i offer no real reduction in running costs but you do get a reduction in performance. They are otherwise mechanically pretty much identical (Infact even the engine block looks the same) so repair costs, servicing costs are the same. The fuel economy difference on the combined cycle between a 320i and a 330i is something like 1.6mpg.
The only noticeable difference you will find is insurance - so check before you decide.
Obviously though the exception to this is if you spot a 320, 323 or 325 at a bargain price - then they are worth going for. But don't seek one out especially as there is little point and you'll soon tire of paying 330 running costs for a 320.
FWIW 3 Series Coupe power outputs:
320Ci - 2000-2006 2.2 litre M54 - 170bhp
323Ci - 1999-2000 2.5 litre M52Tu - 170bhp
325Ci - 2000-2006 2.5 litre M54 - 192bhp
328Ci - 1999-2000 2.8 litre M52Tu - 193bhp
330Ci - 2000-2006 3.0 litre M54 - 231bhp.
Note that the virtually identical power figure between some of those doesnt tell the whole story. The 320Ci develops the same power as the 323Ci but is down on torque and thus not as quick. The same is true of the 328Ci which is faster than the 325Ci despite the similar power output.
A word about trim levels. Prior to the introduction of the revised engine range in 2000, there was no Sport model in the Coupe range - there was one trim level only, which didnt have a name. This changed later on when the range moved to two trim levels, SE and Sport. The Sport added Sport seats, M-Tech branded sills, 18 inch MV wheels, anthracite headlining and an M3 'inspired' (Unlike the 5 Series the Sport bodykit is not the same as the M car) bodykit as well as a few other bits like the Sport wheel and M-Tech suspension.
Prior to the sport model things like Sports seats were an optional extra - so do try and find one with the Sport seats as they are excellent.