I think the Mirena is the better form especially if you cant remember to take a pill daily. Next option would be maybe trying the Nuva ring
I personally have had a wonderful time with the Paragard IUD. It is non hormonal, so you do not get the hormonal side effects of other IUDS, and the only side effect that I personally had was cramping the first two weeks it was in, because my body was getting used to it. Here are some links that may help.
A 'quiz' that may help you decide: http://www.webmd.com/sex/birth-control/birth-control-quiz
Info about Paragard: http://www.paragard.com/is-it-right-for-me/FAQs.aspx
As always, you will definitely want to talk to your doctor about options, but it is always good to be prepared when you go to talk to them. Good luck!!
I would discuss it with your doctor as your doctor knows your history and can help guide you to the right decision for you.
There's the shot, which is good for a while before you have to get another, but if you have side effects, it's not so easy to just "quit" since the hormones are in your system for a while.
There's the pill. If you set a cell phone alarm, it's not difficult to remember it.
There's the NuvaRing, the implant, and the patch.
Then, there are various forms of the IUD. Some have hormones (such as the Mirena as I'm sure you know) and others do not as mentioned above by Breena.
You could also do things like a cervical cap or a diaphragm in conjunction with spermicide, only downside being that you can't be so spontaneous with them and must leave in for a while afterward. The cost can also be a deterrent as they are fitted.