Just throwing my 2 cents. You should buy the plane you are most passionate about. If you're a navy guy, go with the F18. Wait for a possible sale if you have to, and practice with the Su-25T in the meantime.
There are a few beginner friendly, fully clickable modules in DCS; namely the trainers, and the F5. It does sound like you're more interested in the newer aircraft though.
The F18 is by far the best bang for your money... EVENTUALLY. It will provide you with the most versatile gameplay over any other module at the moment. It's also incredibly easy to fly, even a newborn baby still covered in placenta can fly the F18. It's extremely forgiving and the systems are intuitive. The A10C, less so, and the Harrier is probably the worst option for any beginner.
In the end, my recommendation comes down to where your passion is at.