Before Vladimir Putin mysteriously rose to power, Boris Nemstov was widely thought to be Yeltsin's likely successor (in fact, Yeltsin personally informed Bill Clinton that he intended Nemstov to succeed him).
While he was mayor if Nizhny Novgorod (the 5th largest city in Russia, and a major industrial hub in 1991), he was one of the most effective implementers of free markets and liberal economics, and all this while reducing corruption, a tendency he would take with him to his position as Deputy Prime Minister. He rooted out corruption in the banking system, somewhat successfully broke up monopolies in energy and mining, and reformed public housing and social services. In general, he was pretty effective at reducing corruption and increasing efficiency, usually by way of privatization, where he was basically the only man in Russia who managed to accomplish it without just selling everything to oligarchs (though he did some of that, too). He was openly and unabashedly liberal, and had a squeaky-clean reputation. He was arguably the most trusted, and possibly most popular, politician in Russia when Yeltsin resigned.
It's unclear how, but he was effectively sidelined from government shortly before Yeltsin resigned (this coincided with Putin's rise). Let's not get into that, but we can discuss afterwards, when he vocally opposed what he perceived as Putin's rolling back of democracy and reinstitutionalization of cronyism. He started a very short-lived party before semi-retiring from politics, though he continued to be loud EDIT until his murder/probable assassination in 2015.
Nemtsov was on great terms with Western leaders, and had he been elected would probably have strengthened ties with them. His fights against corruption would earn plaudits (and possibly support) from the West, and he'd likely be much more willing to pursue economic integration, since he wouldn't be protecting corrupt domestic companies and institutions. With luck, continued support from the US and EU would help him push through more reforms, and together with economic development, Russia would be joining the West.
Now, let's not get carried away - Russia isn't going to be joining the OECD any time soon (well, they might be allowed to as a symbol, but you get the point). Still, they could be more like Czechia than Romania. Though, I mean, if we're very optimistic, Russia has huge natural resource supplies, and if some of that money made its way into the hands of the people or public services (via taxes) rather than into the pockets of oligarchs, and it was handled wisely, Russia could end up a pretty big economic success surprisingly quickly.