I recommend to start Farming Simulator 19 by getting two tractors. Depending on which difficulty you play (medium or hard), you get a different amount of money. However, a good tractor is important for every work you will do on your farm.
Fendt 500 Favorit
Fendt 500 Favorit - a light tractor for $76,000. In my opinion, this is the best tractor in this class. You can use it to typical activities and as a "multifunctional vehicle". This tractor has a rather good speed - you can use it to transport yields to selling points - and has a front loader attacher. You can also improve the engine from 115hp to 150hp - this makes 500 Favorit one of the most powerful tractors in this class. However, this vehicle also has a few cons: rather limited steering angle and slow start - all in all, these flaws aren't as important when you look at its pros.
Case IH 7200 Pro Series
Case IH 7200 Pro Series - the first of the medium tractors, costs $98,000. Use for works that require more power, i.e. plowing, cultivation and towing heavy machinery. This tractor isn't fast, but this is not a problem. It doesn't have any unnecessary gadgets. 7200 Pro Series has 170hp which can be further upgraded into 261 hp. Buy it, and you won't have to worry about getting a new tractor in the future.
JCB Fastrac 4220
JCB Fastrac 4220 - this vehicle is another great choice. However, you will have to spend more money - it costs $196,000. This vehicle is a good transporter, especially when you live away from the shop. Its default speed is 62 km/h. Upgrade it and you will be able to ride 65 km/h - this makes JCB Fastrac 4220 the fastest tractor in this price range. This vehicle also has a few gadgets and the ability to use four-wheel steering (you can switch between various steering modes).