I tried them along with about 4 other pairs at a try before you buy day run by a saddler.
I was suprised at the difference between them all, I disliked the winderen, and another brand I can't remember. The flex on I thought were no different to my cheap plastic shires ones.
I have the Flex-ons with the partial inclined foot bed. They have been an absolute game changer for me as I can now ride paid free having had a badly broken right ankle and ruptured ACL in my left knee.
Beg, borrow, steal to try some, we all need different solutions and may even need different solutions in different saddles/on different horses. I like Safestyle (very safe, not expensive for starters) but they're not going to suit everyone.
Tech stirrups are very heavy! I didn’t like them personally and sold on.
Vector balance ones are great in my opinion, very happy with them. Also have a pair of old fashioned springer bendy ones (not sure official name!)and they are super comfy!
Hated tech , love slopey flex ons... thought sprenger bow balances were ok but felt insecure to me... it's all personal preference so if yuo can beg and borrow some and try them before you buy them
I personally would recommend against hinged stirrups such as the Bow Balance or original Sprenger ones, all to do with proprioception. If your knees or ankles struggle I'd look elsewhere (saddle, exercise programme etc) but do understand that for a few people they do make a real difference. We need as much proprioceptive feedback as possible, and our ankles should be flexible to allow our knees to be stable, using flexi base stirrups means the ankles have to firm up.