THE E30: In 1985 BMW introduced their first M division model for 3-series, the M3 E30 generation. This car became a legend and the reason is pretty simple. It was RAW, pure drivers car, simple, everything real petrolhead want! The most hardcore road-legal version was called Sport Evolution with 2.5L I4 and 238hp! In total it was made around 16k cars.
THE E36: In 1992 the new generation they continued with new M3, the E36 generation. And it is nowadays almost as beloved as the E30 - mainly because of its new 3.2L I6 engine with almost 320hp. This sounds like big fun just in numbers. The most hardcore road-legal version was called the E36 GT (so rare!). In total it was made around 71k cars.
THE E46: In 2000 BMW introduced M3, which is for many M fans the best. It has again 3.2L straight-six engine with 343hp, and more often features SMG than E36. The most hardcore road-legal version was called M3 CSL - I drove this thing this year and I am speechless, because it is just BEST! In total it was made around 86k cars.
THE E92: And we are almost there, in 2007 BMW started production of M3 E92 - with 4.0L V8 (S65) engine delivering 420hp! It has, in my opinion, the best sounding NA V8 engine ever made. The most hardcore road-legal version was called M3 GTS for E92 / CRT for E90 - both with 4.4L V8 and 450hp. In total it was made around 67K cars.
THE F82: And here it is, the M4 F82. Introduced in 2014, downsized engine = smaller with turbocharging. This is in my opinion what went wrong. It has straight-six 3.0L twin-turbo (S55) with 425hp. It is much faster than previous generations (on track or road), BUT - is it neccessary to be fast?
Is M cars about the speed or about the fun? Sure, the last generation could be fun, but it is filled with electronics, driver has not as much freedom as with e.g. E46. As I experienced, If you are ///M Lover, you would buy older BMW, because it has soul.
Of course, this could be just my opinion, but tell me what do you think about it.