I recommend looking at Moving Comfort (made by Brooks). I like this brand because the sports bras come in band and cup sizes, and not just S, M,L (etc). Additionally, they allow you to try out anything for 90 days before making a decision if you order through the Brooks site. I think I tried 2-3 different ones last year before settling on the Rebound Racer. I wore this with my DC TRI tri top, which does not have a built-in shelf bra. I liked this bra because for the amount of support it gives it still dries quickly coming out of the water. Additionally, you can adjust the strap length. REI also sells Moving Comfort bras, and I think Potomac River Running (DC TRI partner) does as well. However, they might not have as many sizes/ styles in stock. This is my go-to bra for any run, not just tris.
Last fall I bought a tri kit from Coeur, since the DC TRI tri top did not fit particularly well. Coeur now has tri tops without shelf bras, so you could wear whatever you wanted with them. When I bought mine in November they only had tops with shelf bras, so I ordered one of their bras to wear with the kit. I won’t wear this bra to run in with any other top, (although it is perfect for yoga,) but I have found that it pairs well with the shelf bra in the tri kit for running and biking. The bras and tops only come in S, M, L, etc., so I had to find the right combination that worked for me.
Hope this helps!