The first thing is to figure out what bands you are interested in. I use a doublet antenna, home brew ladder line and homebrew balanced tuner. That's not nearly as difficult as it may sound but will take some effort. It will cover all of the HF bands.
The popular choice these days is the end fed half wave. I don't recommend that unless it's a last resort. There are more HF antenna options than you can shake a stick at. How high your tower is and how long of a dipole can fit on your property is another factor.
There are also vertical antennas but you'll beed radials to get good performance. You can buy one or make one. If you use a dipole it can be fed against some radials. Then you'll have vertical and horizontal.
If you're wanting a new rig the Yaesu ftdx3000 is a nice one. The Icom 7300 is very popular and has a lot of features for the money. With the price of older rigs I would buy a new one unless you are looking for something to work on. Buy an Anan 7000 and never look back.
If you're going to work 160, 75 and 40 I would plan on buying an amplifier later. Some purists don't have an amp and don't think anyone else should either but your mileage may vary. Good luck on the test.