Arrow border:
Open border:
Which gives a better user experience, and why?
Arrow border:
Open border:
Which gives a better user experience, and why?
Both examples that you have given are good UX wise, as you have emphasised the active tab and de-emphasised the inactive ones. Good job.
I would however suggest that the arrow border (first one) one is a little better as it is less distracting and lets my attention remain on the content (which is where it should be). When I look at the tabs there is still no confusion as to which tab I am on, and so it's visually subtle enough to get out of my way, but clear enough to give me the information that I need.
My philosophy is to always use the most visually simple design that is able to do the job. Anything more than that, then draws some attention to the design rather than the task.
That said, if this is a critical issue and you have enough budget to handle it, a user study could be beneficial. However as you are taking about two good designs, you will probably have to have a large sample set, which will take a lot of time and money to get any statistically valid result.
If it's not critical that you know this, I would say that it isn't worth the time and cost as both designs are good and have been proven to work.
This is a subjective decision - as long as it's clear which one is selected you're good.