I use Firefox for viewing web pages that I want to be pretty, but I use Opera for everything else. It handles tabs much better, and I can have 20-50 tabs open at once.
I like having a nice big font in Opera, so I go into "Tools->Preferences", select the "Advanced" tab and choose "Fonts" from the menu on the right. I then can set the "Minimum font size (pixels)" to some nice big value, I like 20 pixels.
This works great for almost all websites, except for some that get tricky and set the "line-height" css property based on em widths.
To fix this, go into "Tools->Preferences", select the "Advanced" tab and choose "Content" from the menu on the right. Click on "Style Options" and then at the bottom, you can choose a CSS file for your own style. Here's one that is working well for me:
p {
line-height: 20px;
}
ul {
line-height: 20px;
}
dl {
line-height: 20px;
}