You can buy many elite but you have the chance getting double characters. It is better for clans with good uncommon cards (Freaks, Uppers, Pussy's)
Titanium is better for clans with expensive rares and because you got much cards. But it is better to choice clans with much cards over 10k and expensive rares. Vortex, Huracan, GHEIST, Junkz and Piranas are good examples
Sentinel wouldn't be a terrible choice if you go for elites given how Copper soon to be Cr is still available. But as said, it's still all about luck and even if you picked the best clans you could end up with less than what the worst clans could net.