I thought about doing this for a while and now I've decided to because why not, everyone likes a list of favourite things. This is based around F1 cars obviously. There may be a case of bias here as someone who has a favourite team, McLaren if you didn't know. However, you can appreciate cars from other teams. These cars are not necessarily championship-winning cars, they don't have to be.
Without further ado, in no particular order...
BrawnGP BGP 001
Interesting fact: Jenson Button himself owns the car, only three were made and Rubens used the spare one, as it was in his contract that he would get it if he became champion. There was a bit of an argument between Jenson and team buyers Mercedes, who said that he couldn't have it because he visited McLaren whilst still under contract. Jenson disputed this and in the end got the car. It was the oldest car on the grid when Jenson became champion.
Lotus Type 72
The Williams BMW partnership was a strong one, and in 2003, was competing for the title. It didn't win, nothing could stop the all-conquering Ferrari team. The FW25 won four races with Juan Pablo Montoya and Ralf Schumacher. Marc Gene replaced Ralf at the Italian Grand Prix after being involved in a testing accident. The reason why I like this car is that Williams were at their best for some time and with BMW were the strongest challengers to Ferrari for a short time, along with McLaren-Mercedes. The FW25 got Williams to second in the Constructor's Championship in 2003.
This next car is probably my favourite F1 car ever...
2005 saw a close Championship between two teams, McLaren and Renault. Kimi Raikkonen was up against Fernando Alonso for the Driver's Championship The McLaren MP4-20 was faster than the Renault R25 but the Mercedes-Benz engine was unreliable and cost McLaren both titles. The reason why I love this car so much was when not blowing up, Kimi was able to pull off some incredible displays, getting pole at Monza with a full tank of fuel before getting a 10 place grid drop because he changed his engine. Then there was Suzuka, where after qualifying 17th, stormed through the field to win the race. The MP4-20 is also notable for achieving the highest speed ever recorded for an F1 car during a race. At Monza, race winner Juan Pablo Montoya hit over 231mph when he won the race. The MP4-20 is a car that deserves to be remembered as a great F1 car.
And yes, the MP4-20 is the car in the blog background.
I think that's the list, there could be more but these are the top ones for me. I noticed there are no Ferrari's on the list. That's mostly because of the dominant Schumacher era which was a dull, red blur.