Hi,
As pointed out, individual scars may require different treatments, so it is really wrong to say that TCA cross is the best treatment for acne scars. TCA Cross is really effective for ice pick scars but may not be worth the risk for rolling type scars.
Both the Venus Viva and Acnexel treatments use good technology for acne scar treatments, and are able to get some of the best results without the downtime of ablative fractional lasers like the CO2. I still use both fractional CO2 and RF/heat in my practice, but interchangeably depending on my patients' needs and demands.
I would recommend you give it a try if you are tempted, since the treatment is safely administered by doctors. The downtime should be quite minimal in comparison to some other acne scar treatments!
Hope this helps!