It's my second car now, and knowing it will happily sit there for 2-3weeks and then turnover first time is great.
A TVR might be more exciting and powerfull, a classic car might have more character....but reliability (both costs and the time it takes to sort these issues) would both really put me off keeping one. For me the Z4 has the right blend of character and every day reliability.
My dad sold his MG a couple of years ago for this very reason and often talks about now buying a Z3/SLK to replace it, the Z4 ride being a bit harsh for his tatses!
When I had mine I loved it when you first started it up in the garage and the noise it made bouncing back off the garage wall and that never failed to raise a smile and then I just wanted to get on with driving it.