To add to my introduction post..
My favorite Lego series was the train and city as they existed late 80'ies/early 90'ies at the transition of 12v to 9v, and the mid-90'ies also saw the most epic Technic sets ever, the 8880 supercar, 8868 compressor truck and of course the Space Shuttle. For me, Lego has been going steeply downhill ever since then, with this piece as a sad epitome of everything that Lego should not be. I initially strongly disliked the studless Technic series but after getting some experience in building with it I can see some of the merits, still, Technic sets without studs make me cry a little on the inside and I think Lego would do well to reconcile this new technology with its old roots.
Now, on to trains. I love the 12v series for its complexity and tech level they offered. All the remote functions and different sets offer a huge level of playability and customization both in the conventional and non-conventional sense (modifying Lego parts manually). Especially the later 9v and early remote control series trains I hate with a passion - I really cannot stand their plastic futuristic look. PF is a different story, because while they lack the complexity in tracks and accessories that 12v offered, they do bring about a lot of hugely detailed sets with many small pieces (see link above :)) and good customization for the locs, engines and transmissions. It is however for their lack of technical accessories that I plan to stay clear of them, and will happily collect and play with the 12v sets til kingdom come.
That'll be my little rant for today, Sok out.