I can't say that I'm particularly thrilled about most of the available options.
Of those offered, the one I'd be more interested in would be Jack Swagger. During their feud, which was much more entertaining than I think most was expecting in my opinion, they left the door open to possibly restart the feud. Even though Swagger lost, he either never tapped out to The Accolade or lost due to interference from Bo Dallas. If Rusev goes onto capture the United States Championship, I'd be open to the notion of Swagger being the one to take the title from him at WrestleMania XXXI. Give the fans a feel good moment, end the reign of a Russian sympathizer that's made a "mockery" of the USA by being WWE United States Champion and gain some measure of redemption.
Big Show has nothing to gain by beating Rusev. Show's at a point in his career where his best assets are putting over younger guys on their way up.
If the reports on Angle are true, he won't be in WWE anytime soon. Allegedly, Angle was offered a full time deal by WWE and turned it down. In my opinion, and that's all it is mind you as I have no proof on anything, I don't believe WWE was too interested in bringing Angle back anyhow or they'd have offered him a part time gig as he was hoping for. They know Angle's getting older, he's not what he used to be and that he most likely can't handle the physical strain of a full time WWE schedule. If they were interested in bringing Angle back, he'd still have to be medically cleared after undergoing WWE's numerous medical tests. Since he wasn't medically cleared by UFC to participate in the 10th season of The Ultimate Fighter back in 2009 and with WWE's strict standards, Angle might not be given clearance to wrestle in WWE.
As for John Cena....Hell no. The last thing Rusev's career needs is for him to be offered up as another in a long line of sacrificial lambs to the resident Superman of professional wrestling.
As far as Mark Henry goes, not a chance. He's already beaten Mark Henry decisively in two matches, forcing him submit to The Accolade. Like Big Show, Henry's best days are behind him and while I wish WWE would've started doing with Henry a full 15 years prior to what we saw in 2011 C'est la vie. His best use is to ultimately put over younger guys.
Brock Lesnar's much, much too expensive of a commodity to be used to decimate a guy that's, currently, a mid-carder. Brock Lesnar's deal is structured similarly to what we saw and what we see of a lot of MMA fighters in that he competes only a small handful of times a year. Lesnar's payout for his entire MMA career is as follows:
Dynamite!! USA - vs. Min Soo Kim - $170,000
UFC 81 - vs. Frank Mir - $250,000
UFC 87 - vs. Heath Herring - $450,000
UFC 91 - vs. Randy Couture for the UFC Heavyweight Championship - $450,000
UFC 100 - vs. Frank Mir for the UFC Heavyweight Championship - $400,000
UFC 116 - vs. Shane Carwin for the UFC Heavyweight Championship - $400,000
UFC 121 - vs. Cain Valasquez for the UFC Heavyweight Championship - $400,000
UFC 141 - vs. Alistair Overeem - $400,000
So, for fighting 8 times in mixed martial arts, Brock Lesnar made a total of $2,920,000. That's not counting what he made from various endorsement deals. I'd be willing to bet that Lesnar makes somewhere in the mid six figures for every match he works in WWE. It's too expensive to use Lesnar against someone on the level of Rusev at this point in time.
As far as Sting goes, take the stuff I said about Angle's injury issues and apply them to Sting. Besides, you know how bad that'd make Rusev look. No matter how you slice it, no matter how much you might be someone who loves nostalgia, there's NO FRIGGIN' WAY that a wrestler can job out to another wrestler that's 27 year's his senior and not look bad. If you want Rusev to look like a complete chump then, by all means, have his first big loss be against a senior citizen.