Been down that road. After 7 ZTs bought a 2007 320d M sport. The difference is night and day between the two. The Beemer is obviously more modern and has the benefit of continual redevelopment where as the Rover was designed and produced and very little changed in the production years. The beemer is a great car but the parts are astronomical if an ABS pump goes etc. Upgraded to a 10 plate 320D M sport running a std 184 Bhp and it was a belter but didnt have an ounce of character like my ZTs did.
All modern cars will have better equipment and engines thats life and many cant realistically continue to use a 14 year old car such as the R75 or infact any car.
I now have a focus ST and its a cracking car and the best bit about it is the availability of used parts at really low prices where the BMW parts were upto 3 times the price!
Judge a car on how many are on our roads and what the retail prices are like. Some people hate BMWs some Audis but make your own mind up. There are plenty of indys now who specialise in BMWs etc so shop around when servicing and buying parts.