Real quick, I think Riza being a highly trained soldier should place her at Street level physically, but this isn't the place for revisions. Although even so, Barry would take physicals regardless, since he scales above bullets
Barry Advantages:
-AP/Durability (His profile is just really self-explanatory. Just based off of Ronny related feats alone, its clear who has the advantage here)
-More skilled in martial arts (Along with his marine training, he could also outlast
one of the greatest Taekwondo fighters on Earth in a close-quarters battle)
-Stamina (Consistently just brushes off stuff that would definitely require Riza to catch her breath
-LS
-Stealth (He nearly has a cartoonishly busted level of stealth proficiency,
as outlined on his page from just this feat alone)
-Higher attack speed (Keep in mind, speed equalization doesn't change this advantage. The muzzle velocity of Barry's fastest shooting guns are faster than Riza's own weaponry)
Riza's Advantages:
-More versatile (Consistently carries more firearms on her than Barry does)
With how this fight's set up and based on their preferences in combat, lets be honest. This won't come down to a physical confrontation. It'll likely be determined by gunplay. Its trickier for me to say who the better shot is. I think arguments can be made both ways given how if you look at Riza's feats of gunplay and then Barry's...they really aren't too dissimilar. So why didn't I note this down at all above? Its a battle between marksman so you think whoever has the better aim and quick draw would take this, right? While not untrue, I'd like to bring up Barry's stealth again. Both are starting this battle 20 meters away from one another out of sight. This is definitely in Barry's favour. Keep in mind, I won't discredit Riza here at all. As seen in some of her best moments as a sniper, she clearly takes good advantage of keeping herself out of sight. But between her and Barry? Berkman getting out of sight is downright terrifying for Riza, who certainly doesn't have the same accolades in this department. Especially given Barry has been carrying hits for a long time, completely avoiding suspicion from the authorities, with all existing traces only ever coming as a result of Fuches' own spite, a guy close to him who literally convinced him to be a hitman in the first place
This is pretty close when you base this solely on their capabilities as marksman, like I said, you can honestly argue either way. But Barry's additional skills are a strong edge here
Voting Barry Berkman