I like bras with a smooth back and avoid those that fasten with hardware. I had purchased some Barely There Women's Customflex Fit Active Wirefree bras with the hopes of using them under clothing.  The straps are wider than I would like, and they end up showing under most necklines.  The bras in general are rather wide, which means the bra is that much warmer when the weather is hot. The Customflex Fit Active Wirefree bra does provide more coverage for the headlights, if that is a concern.  And they are comfortable in cooler weather. I bought the green and the dahlia colors, which are lovely. I am a 34A, and the Small fits me well. In truth I find the Fruit of the Loom Spaghetti Strap Sports Bras to be the most comfortable. Only problem is, they do not provide enough coverage for the "headlights", which become prominent when one is cold.
 Personally, I like the Champion C9 Premium Maximum Performance sports bra with the much narrower straps (which happen to be adjustable).  I've only seen them sold at Targets; I hope Amazon starts selling them.  They too provide better coverage for the headlights.  They are comfortable, but not as comfortable as the Fruit of the Loom Spaghetti Strap Sports Bras.
And yes, all three sport bras--Customflex Fit Active Wirefree, Fruit of the Loom Spaghetti Strap, and Champion C9 Premium Maximum Performance--give one the uniboob.  That seems to be the price for hardware-less comfort.