I'm just starting to learn Japanese but I can't choose between those two :/
I've used Genki book 1 up until chapter 10 and I have to say it's a really good method that eases you into the language. If you can get the audio CDs it's even better!
I don't have much experience with the other book, though I have a Malaysian version from that series (if I'm not mistaken) and I keep wishing it was like Genki lol... So I'd say: Go for Genki.
And the claim that Genki has 9 volumes is untrue.
You have: Genki book 1 and 2 ( gets you to high JLPT 4 - beginning JlPT 3, if I'm not mistaken),
And when you've finished those, there are two other books you can get from the publisher that teach at an intermediate and advanced level.
But you don't HAVE to get the last two books, you can always look at other methods once you hit intermediate since most of these books teach pretty much the same stuff.
And if you don't have much cash to spend, "Tae Kim's Guide to Japanese" seems to be recommended a lot by others too.
It's free and readily available, just google it.
Good luck!:)
I think there are so many free resources out there that you should at least try teaching yourself before you start spending money. I.e.
http://www.memrise.com/courses/english/japanese/ ;
https://www.youtube.com/channel/UC0ox9NuTHYeRys63yZpBFuA
Check out your local libraries too.
Japanese Kanji & Kana by Tutle is a VERY GOOD BOOK.
It teaches you Katakana, Hiragana, 3 Types of writting in Japanese, 2,200 Kanji.
What i recommend is Getting that book, getting a writing book / dirary and than every day, try and memorize and practice Every bit of Hiragana than over time move onto Katakana, than read through the grammar rules than you should go on from there. Will take time, you will have to memorize a lot of stuff, you will have to write it down and practice recoginizing it, writing it and reading it However it will pay of. I also recommend on the SIDE (as an extra) to get "ear worms rapid japanese" Volume 1 and Volume 2. These are audio discs that help you pronounce and remmber easy words in a fun way with some cool groovy music.
What's "Genki"? Is it a book?website?
I think there are nine volumes of Genki. If you only have the first book it will only teach you some things. One complaints I think I had with the edition I had of Genki (circa 2005) was that the characters were to small to examine carefully. But I think there might be more information in one book of that the the "teach yourself" volume. (from a British publisher, no?) If possible, read them both.
