Being in the middle is a good thing for medium cymbals; it makes them very versatile. If you want to be able to play multiple genres without having to swap in a different set of cymbals every time you switch, then you're definitely looking in the right place. They may not be as loud as heavy cymbals or as precise as thin ones, but the advantage medium cymbals have is that they can cover for both - and their balanced tone makes them the first choice for plenty of styles as well.
Choosing medium cymbals for your setup starts with deciding exactly what you're looking for in terms of performance. Do you want cymbals that really stand out in looks as well as sound? If so, check out options like Meinl's Byzance Dark Raw Bell Ride or Classics Custom Dark Ride Cymbal. You could also search by era, with cymbals such as the Stagg Black Metal Bell for a throwback to the rough handcrafted days or the Zildjian Gen16 series for something more futuristic.
If there's a particular drummer with a sound that you'd love to replicate in your own cymbals, it's definitely worthwhile to keep your eyes peeled for the signature-model medium cymbals here as well. Cindy Blackman fans will definitely love the performance of her signature Istanbul Agop line, for instance. A few other examples are the Paiste Joey Jordison Signature Series Alpha Hyper Hi-Hats and Sabian Neil Peart Paragon Crash Cymbal. These instruments are designed to meet the exacting specifications of the pros, so you can definitely count on the quality of their craftsmanship.
When most people think of drums, they think bass, toms, and snares. But drummers are well aware that cymbals are an even more discriminating choice. The impact that they have on your sound is huge, and when your goals are balance and versatility, medium cymbals are definitely the way to go.