i've had braces before, but not invisalign. my retainers are similar to invisalign though, with the only difference being that my retainers are not made to change the alignment of the teeth and instead keep them in the same place. im guessing the only annoying part of invisaligns is that you'll have to take them out every time you eat and brush your teeth.
for braces, you'll have them tightened depending on the dentists' schedule/plan for you, but it might be around each month or so? the tightness of the braces were painful for me to be honest, as my teeth were extremely crooked. not to mention the ulcers i would get a lot (though they do provide wax for the brackets which made it less bad i suppose). another thing i've heard is that invisalign is more comfortable than braces, but i wouldn't be able to compare the two experiences as i've only had braces. braces are quite expensive to repair, as are invisaligns, though im guessing you'd be more likely to break the braces, especially if you eat the wrong foods (another annoying thing about braces - the amount of foods and drinks you have to be careful not to eat or drink). you might find yourself being more careful with cleaning your teeth because of the fear of them becoming stained more than you would if you wore invisaligns.
i think braces are better for those with very crooked teeth from what i've heard, so if you have very badly misaligned teeth i'd probably go for braces. but i guess the main advantage of choosing invisalign instead of braces is that it isn't as obvious-looking as braces, so you could consider the aesthetics for this too. invisaligns sound much more better imo, but maybe im wrong haha, hope someone who has used invisalign before replies.