SS lines are an upgrade in heat resistance, (short term) abrasion resistance and (arguably?) feel, but have their own liabilities. They tend to have significantly lower lifespan and more likelihood of a catastrophic failure than rubber lines, with the added bonus of being harder to inspect for nascent problems. There's a reason even ridiculously specced cars like the Porsche GT3 come from the factory with standard lines instead of teflon/ss.
For a dedicated race car, absolutely braided lines, all the way, with a proper maintenance and replacement regime like everything else on a dedicated race car.
For street use, especially in environments with harsh conditions (salt/sand on the road, low temperatures, etc.), if you're not swapping out braided lines every couple of years or quicker, you could be setting yourself up for a very bad situation.
For my use and my driving environment, I'd much rather have the piece of mind of OE, thoroughly tested components with a proven record of reliability over small improvements in feel in a safety critical system. Not enough to stop me from putting better brakes on, of course!
