Overland:realistic crawling...can go on carpet and all the rough terrain..
Racer:good for RCP tracks and smooth surfaces
F1:REALLY, smooth surface and RCP
So its really what kind of terrain your driving on...IMO you should get the OL because it can take all the terrains....Your choice
Any of them is a good choice, The Overland has the offroad ability, among other things. I find the racers are quicker and still a good choice as well.Picking one over the other is difficult at best. I slant toward the racer series because those are easier to find parts for, and I like the speed and handling. The F1 has never been a favorite of mine with it's open wheels and it seems the hardest to find parts for.
Do you have plenty of smooth surface to run on,garage or around the block? If yes the MiniZ racer is a great choice.
The mini F1 cars are only good for a track or table top smooth surfaces.Any tiny debris will make the car fly at speed.
Overland trucks will be ideal for most people as they do not have larger smooth surfaces to run them on.And you can do some limited off roading with them.