Of course, the following list is by far not complete but describes only the models I personally use most frequently.
All statements regarding sound and suitability represent only my personal opinion and don’t claim to be generally valid!

Brand: Description Type: Pricing: Homepage:
AER The AER company is known first for their excellent acoustic amplifiers. It’s less known that they also produce some decent pickup-systems for acoustic guitars. combined Piezo / microphone system about 250,- EUR https://www.aer-music.de
Fishman Fishman is one of the pickup manufacturers with the longest history and also probably the most popular brand as well. They produce a vast variety of pickup systems from economic OEM- to more elaborate models various Piezo- and magnetic systems with or without additional microphone from 150,- to 450,-EUR http://www.fishman.com
Headway Headway systems never became very popular, but when you are looking for a very smooth and round amplified sound, they are a good alternative. undersaddle transducer, coaxial ca. 250,-EUR http://www.headwaymusicaudio.com
L.R. Baggs LR Baggs is for many years one of the top-notch manufacturers for acoustic guitar amplification. Most of their pickups base on a flattened coaxial (“Element”) transducer, sometimes combined with an internal microphone (“Anthem” system). In addition, they produce some decent magnetic soundhole pickups (M1, M80) for steel-string guitars and an internal soundboard sensor (“Ibeam”). For me personally, LR Baggs is one of my first choices amongst all pickup-brands. coaxialer undersaddle transducer, soundboard transducer, magnetic pickup, internal microphone from 200,- to 400,-EUR http://www.lrbaggs.com/
MiSi MiSi is one of the newer brands in the market. Most of their systems use an LR Baggs “Element”-sensor, but combine it with their own electronics. The unique thing is, that they use some kind of “super-capacitor” instead of a batterie to supply the power to the preamp. By doing so, though it’s active systems, you don’t need a battery anymore, but charge the preamp through an external charging device instead. Soundwise, they are pretty good as well in my opinion, good choice! undersaddle transducer (coaxial), sometimes combined with an internal mic from 240,- to 300,-EUR http://www.mi-si.com
Shadow The German Shadow company is also one of the “old players” in the market. For many years, I wasn’t very happy with the tonal results, but for a couple of years, I have the impression that they really caught up to their competitors and now produce respectable pickup systems for a fair price. various platforms from 150,- to 300,-EUR http://www.shadow-electronics.com
Belcat Belcat is a Chinese pickup manufacturer. They are surely not top of the line, but have extremely competitive prices. In my opinion, they can absolutely compete with the less expensice Fishman system e.g., but for an even much lower price. If you are looking for an ok-sounding pickup for little money, it’s a perfect choice! various from 60,- to 100,-EUR http://en.belcat.com/