Having taken an FKK tour in February, I have been to all three of the aforementioned FKKs and concur with most of the sentiment expressed by Woolfox.
The main differences I found with the three clubs were size, ambiance, youthfulness, and price.
1. Samya - The girls here are often more youthful, but it is more like a pickup bar. I went here on a Friday night and most girls were having fun around the first floor bar. A saxophonist played at times and some of the girls danced nude inside the bar area. On this night, most girls were totally nude, save a pair of heels. Prices were 50E for first 30 min, 25E for second thirty, and 25E for CIM. DATY and BBBJ were standard. The main difference here is that you need to approach the girls, sometimes difficult to do if you don't have a language in common. On one hand, I had one blonde spinner that looked like a hot babysitter turn me down for a romp upstairs and I had another girl who reminded me of my HS French teacher trying to avoid me. On the other hand, I had a nice time upstairs with a Turkish girl who had a genuine O from DATY. The showers and lockers in the basement were quite good. One nice benefit is that some of the girls also use this area to shower and prepare themselves on arrival. There is an enclosed patio area in the front, which was seldom used when I was there due to temperature.
2. Babylon is more like the usual FKK atmosphere, with a quieter bar on the first floor. I found the girls a bit easier to approach than at Samya, but on the quiet Wednesday evening I was there, it seemed that I was almost the only guy interested in some erotic activity, which gave me a leg up, so to speak, lol. I found conversing easier here than at Samya, and all the girls were interested in a session (also unlike Samya). The girls here are also easier to identify based on their website photos, so it is easier to target a girl of interest. One girl took a visible shower while I was in the basement sauna, then came in to relax (later I found this to be her MO). A gentle massage to her foot, then her leg, led to some nice kissing with her in my lap, which then led to an extended, fun late night romp in the open kino on the second floor. I felt like I could have declined at any time in the sauna, had I wanted to do so, so I didn't consider this a 'wanna dance' pushy approach - more like a real girlfriend coming in to join me.
The rooms are much bigger and nicer than at Samya and the kino is HUGE. I had two delightful sessions out in the open in the kino. Although a NRW club, the prices were more Hessen, 50E for first 30 min, 50E for subsequent 30 minute blocks, and 50E for CIM. DATY and BBBJ are standard, but anal (which I did not explore) was a 100E option. Pricing and an introductory tour by a pretty lass were provided at entry.
3. Bernds is very much like described by Woolfox, but I found no stunners here. Not saying that the ladies were ugly - but if looks are your sole criteria, there is better fare elsewhere (like Oase). On the other hand, there are no extras/options here - everything that a lady does is standard pricing and they are very generous with their time. Pricing is 50E per 30 minute block, period. The facilities are clean, but not nearly as nice as Samya and Babylon. There is no kino, but there is a small sauna in the basement and functional lockers and shower on the first floor. The rooms are also functional and sufficiently large, situated in the basement. Thursdays are dessous days, when I attended, and the girls were not nude, dressed instead in lingerie.
As in other NRW FKKs, you have to approach the girl, which for some reason seemed easier to do in the downstairs bar. But unlike Samya and more like Babylon, approaching a girl is pretty easy and all are interested in a session. The girls will also start to DFK and give you an introductory BBBJ right out in the open, and if you prefer an open session, one available room has a large window, overlooked from the downstairs bar.
With a rented car, the distance between the clubs is about 30 minutes, a little longer to get to Golden Time, and about 90 minutes from Oase in Frankfurt. In Hesse (Frankfurt area), the girls approach you for a session and it is harder to find some peace and relaxation between sessions. On the other hand, they are of course more approachable.