Of the serious contenders there, I'll offer my $0.02.
Figo wouldn't be the worst choice, but he's very young and has no experience at such an administrative level. He's only not been playing for 6 years at this point. If he seriously looks to make a bid for FIFA presidency at some point, a position in the Portuguese FA or UEFA is more fitting at this point.
Platini is absolutely no better than Blatter. I hope the public is made very aware of this, he fully supported the World Cups in Russia and Qatar, and appeared to have his son get a nice cushy position in Qatar for it. He's the same kind of slime that Blatter was and only managed to keep his head low because others have been more involved and more blatant.
Prince Ali bin Hussein is also very young, although he is the president of the Jordan FA and has been the Asian Confederation President since January 6th, 2011. It's hard to say how much would change under him, or if he can expect support now that the flood of new candidates is open. Overall, less tainted than Platini by far, and more proven than Figo by far. How much that will be taken into consideration will come to be seen.
If I had any measure of impact on the eventual outcome, I would urge people to support Michael van Praag. A former Dutch referee, former chairman of AFC Ajax, and has been president of the Dutch FA since 2008. Very outspoken against Blatter for a long period of time, he had separated himself from that administration much prior to the current controversy. He has proven that he is, at the very least, a significant step in the right direction from the likes of Platini and Blatter, and has experience with an FA more in the public eye than Prince Ali. It would also be unlikely that he would return the FIFA presidency to the dictatorship that it has been, as he is getting a bit long in tooth himself, being 8 years older currently than Sepp Blatter was when he was elected.