I"ve had a 2000 C280 for almost 3 years now. Mileage from 35m to currently 60m. Love the car and so far relatively trouble free. The advantages to the 98-2000 models are the keyless entry, no antenna to break, and electronic A/C. I settled on MY 2000 because it was suggested the 722.6 tranny was well sorted out by then. The M112 engine has the harmonic balancer problem so check and see if the updated part is in there. Plenty of threads on this.

The only things I have done to it is replace the camshaft position sensor (CPS) which causes the sudden stall syndrome (SSS) that many have complained about. I've changed one o2 sensor and another one has recently starting throwing a CEL but the light goes out after a day or two. I just changed the plugs and one or maybe two were fouled, hopefully due to just age and nothing more serious.

glenmore
1991 300CE
2000 C280
1990 LS400