Imho only buy new bloods on the day of new releases.
http://urdb.kirlad.net/packs.php could help
but personally i've always bought titaniums since my collection's still low anyway. I guess once you have over 50% of all cards in all clans, then you can go for the highest clintz/pack as calculated by urdb. But before that time, going for titaniums and choosing the appropriate clans would surely help your collection the most.
Kirland's calculations are obiviously flawed, I wouldnt trust them to make decisions.
Currently NB is great choice if you want lottery style, it has huge potential. Also for new players NB is good choise since it gives out better cards in average than any other pack (since it lacks the old clutter.).
But in the end the difference between NB, good picks on Classic and Silver pack are actually marginal, they fall within 20% of each others value on the long run and each one has fair potential for lousy pull.
If I were you extended or elite are perfect tbh. Those can expand your collection and you can find some great pulls from there.
Strictly speaking, I've bought titanium. Got about 60k worth of stuff. Good for getting rares that I specifically might need.
I also bought 8 packs of Elite and got 110k worth of stuff.
And then recently did 16 packs of newblood...got a Thorpah and that was about it, totally about 36k total in clintz.. (On friday) Pretty much one of the worse things ever. People who say newblood, well don't do it tbh. Not cause of what happened to me, but there really isn't many cards in there that are decent compared to the older cards. Also, you will make more clintz per creditz if you do Elite/Extended.
After that, I bought 4 packs of extended and got 40k worth of stuff haha.
Soon after I was mad I bought another 10 packs of extended and got 100k worth of stuff again.
Tbh, if you really look at all the cards that are available in UR, you'll notice that NB has like a small amount of cards worth over 15k. You have a better chance of not getting the same crappy card over and over again with such a small selection if you do Elite/extended.
Elite/Extended for clitnz and increasing your collection. Titanium for getting select clan rares you want for your collection. New blood if you want troll yourself getting the same pulls over and over again.