Right now, Edo Deidara is waaaaaaaaaaaaaaaaaaay more useful. However, long term, Susanoo Sasuke is going to be much more valuable. In my opinion, I say go for Sasuke. A year from now, you're going to wish you had gotten Sasuke, because his skill books make him very good.

I'll say it like this. Susanoo Sasuke is usually the last one alive in china GNW. Skill broken, he becomes god tier. If you don't believe me, watch the chinese videos. Almost everyone is running around with Sb Sasuke. There is a big reason to that. He literally becomes tankier than 80% of the tanks out there. He hits all 3 fields very hard, and his immunity to edo deidara is extremely useful. He is immune to damage from Shisui mystery, deidara mystery, or any ninja that hits with pure ninjutsu. Edo hiruzen is good, unless he is in a team that doesn't buff him. I have seen him in teams that don't buff him, and he hits very meh :/ a lot of people don't realize that. He can wipe fields, if you have superior battle power. But you can do that with aoe damage from any ninja. So again, in my personal opinion, I feel as though susanoo sasuke will be better for you in the long run. Gauging from china, susanoo sasuke is used more than deidara.