They are both excellent introductions to the game. Presented in workbook format. The speed baduk goes a fair bit faster through material than level up, so may be more difficult to follow without assistance. Also, speed baduk is a bit difficult to acquire as it is out of print. The level up series goes at a great pace and takes you pretty simply to about 10k. The follow up series Jump Level Up goes currently to about 2k but is more difficult and will require more study. I highly recommend both series, but for someone without a teacher better results will be had with level up. If you have the resources I would suggest first level up then speed baduk then jump level up. Jump is still being developed it seems, book 6 and 7 are Korean language only at the moment, and beyond that two other series are planned. High level up and top level up.
Btw: the first few books in both series may seem too easy, but I still can recommend them as sometimes there are fundamentals which are missed without structured learned and going back to get those can be helpful.