I wouldn’t say that old lenses have nicer character than new ones since that is a matter of taste and lens designers pay more attention to smooth bokeh today.
Which adapter you need depends on the lenses you want to use, every major manufacturer in the 70’s and 80’s had it’s own bayonet and you need one adapter for each bayonet you want to use.
That swells to 79 or so the number found circling the giant planet since Galileo spotted the first of them with a homemade telescope more than 400 years ago.
The long answer: There are many old lenses which deliver very good image quality. Here are two examples of very fine lenses: Many people worry a lot about the sharpness of a lens and then upload their pictures to social media where it is impossible to tell an excellent from a decent lens.
If you plan to use more expensive lenses I would recommend a more expensive adapter like the one from Novoflex*.
The Novoflex Adapter (which I have reviewed here) has lower tolerances and is more durable than the cheaper Chinese adapters.