I have a suggestion that as of yet I haven't seen mentioned. Now, I can't compare because the only other textbook I've used is "Nakama" and I've glanced through "Youkoso!" and "Genki." Anyway, my suggestion is "Introduction to Modern Japanese" published by Cambridge University. It has a different organization from most other textbooks - for one you start with all three writing systems, so you have to know Hiragana and Katakana before you use it. Each chapter is centered around a passage, which gets progressively more difficult. There are 50 lessons, and it's designed so that each lesson can be completed in a week though you may want to take longer than that. So, basically 1 year to complete the whole thing - but again, I suggest you take as long as you need. It covers everything necessary for daily conversation and explains a lot of the idiomatic expressions you will encounter. If you get the supplementary workbook, which I suggest you do, you will have plenty of lessons to reinforce everything. You have to have the discipline to study on your own, though. Every week.