I believe that photobucket is a better image uploading service than Imageshack, personally. I've been uploading all of my images there since I first came to ZFGC, and they're all still there. It's great to occasionally go back and view them all. I've also very rarely had any problem with downtime, and nobody ever has to click on a thumbnail of one of my images to see the entire thing. Other than the filesize limit, I have absolutely no qualms with photobucket, and intend to continue using it for all of my images for many years to come.
Of course, this is just my opinion. You can use imageshack if you'd like, but I personally find that photobucket is an excellent image hosting service.