Modafinil was great for me when I started, but I think it's more for productivity than focus - so it's still easy to get distracted while on it. For some reason overtime it started giving me anxiety, even though I was doing them only 2x a month and breaking them down into quarters. I was taking them with caffeine, so that could be the cause, but either way I never really saw increase in revenue while on them and I just stopped a few months ago.
I love Adderall for focusing on tasks that I don't want to do and don't want to outsource. I just don't want to rely on them too much (who knows what kind of long-term side effects they produce) so I only take them when I have a deadline coming up. I still have one laying around that I haven't touched for months, but will probably end up taking in the next few weeks. I also break them down into quarters with a cup of coffee to kick it up a notch.
If you really don't need these drugs (it's pretty easy to get a script if you know what you're doing), just eat good, exercise, sleep well, and keep your mind stimulated. It takes some time, but to me it's better and more productive than both of these drugs combined.