Edited Mar. 12, 2017 at 12:49 a.m.
I think the Leafs' best bet is to target a player who could POTENTIALLY reach top-pairing status.
When thinking about RHD, names like Josh Manson and Brett Pesce are often brought up but those two players will likely not be made available to acquire. If anything, Anaheim will trade Vatanen before risk losing Manson, and Carolina don't really have strong RHD depth after Faulk and Pesce.
A name I've brought up but many others haven't that I think has true potential is
Colin Miller from the Boston Bruins.
He's a 24-year-old RHD and has been playing on the Bruins' bottom-pairing, which is hilarious, considering how much better he is than either McQuaid or Carlo. The Bruins clearly don't know what they have with him, and with McAvoy possibly joining the team next year, he could potentially be had at minimal cost compared to much more high-profile d-men around the league.
He's real solid defensively, can skate, and make effective breakout passes. I think he would be an ideal partner for Rielly.
And he was the captain of the Soo Greyhounds when he played in the OHL so Kyle Dubas probably knows who he is and might already be on his and the Leafs' radar.