Fins advice

Hi all, looking for an advice here. I have a pair of old long rigid fins and I think I'm gonna ditch them, they are good to stretch ankles and load quads but don't help kicking technique. Yesterday I tried a friend's pair of middle size flexible fins and it was an eye opener: not only they stretched the ankles, but also the feet (which my fins don't)! I suddently realized how stiff my feet are and how foot flexibility matters as well. Moreover, comparing to my fins, with these shorter ones I could kick with better technique (legs not too separated) and flip turns were as comfortable as they are barefoot.

So I'm going to buy a new pair of fins. Do you have any models to recommend? My friend's fins are not branded and currently out of market. I'm looking for a pair of middle size flexible fins. As far as I know short fins (zoomers) are mostly for sprinters because they allow fast kick cadence. I'm not interested in this. I want to use them to stretch ankles and feet, improve kick technique and fluidity (and convince me to do some more kick sets where I'm always lazy at!). Any feedback on alpha fins by chance? They look cool but I've been told they are floaty and I wouldn't like this.

Thanks in advance,
Salvo

I was using the below ones, nice and very practical to wear on and take off, also effective for developing plantar flexion.
http://speedo.co.za/wp-content/uploads/2014/10/Fitnessfin_002.jpg

Realized that equipments dont contribute on my swimming, so that now I am not using any equipment except and old goggle's rubber for tieing my ankles while working on my pulling, all other stuff such as paddles, fins, parachute, pullbuoy, snorkel are staying in my wardrobe as an inheritance to my children, i have a very light back including a trunk, towel, tempotrainer, goggles, silicon cap

P.S: please note that also drag trunk/or parachute is useless, it damages your natural rotation and you get used to the bad rotation. Tethered swimming maybe good for gaining power a bit, but mustnt be higher than 10% per week, it also teaches you the bad technique.

Thanks NC. About tethered swimming I suspected the same.

Salvo