Methadone builds up in your system, they start you on a lower dose and up it every day until you feel OK. Plus you have to go to a clinic to dose, if you are consistent you get 'take homes' so you don't have to commute. Also, since it builds up in your system you can miss a dose or two before you start to feel WDs, so that is a fail safe.
Suboxone works instantly, and I had more success with this. You let it dissolve under your tongue and it kicks in and you are good to go for the day. Problem with these are they taste like absolute shit, and they are a hassle to get prescribed from what I understand. I would always have a few on hand for a rainy day.
The withdrawal from methadone is much, much worse than suboxone. Both suck because they have a longer half-life (compared to dope WDs it is more mild but prolonged), but I'd rather kick subs over methadone. Hell I'd rather kick gear over methadone. Yeah it sucks but just medicate yourself heavily and the worst of it is over in 3-4 days.
HTH..