Verdana as the sans serif of (my) choice (though it'd really be Lucida Sans, but it's not an option ...). And if you even touch Comic Sans, I'll ... whine about it (and leave your site).
Arial / Helvetica is available on many OSes, whereas Verdana, Tahoma, Trebuchet MS are generally on Windows only. If many of your users are using Linux and you want a consistent look across OSes then it may be better to use Arial. Arial is common, but that doesn't mean it's the best It's upto you which to choose based on what you like...
I prefer "Verdana, Arial, Helvetica, sans-serif", looks simple, is user friendly and easily readable. Its only for browser viewer not for printing.
Like many others, I use Verdana, this font is well-known to be one of the best for websites (easily readable on-screen!).
I was using all time Ariel but good that you post this I never used that Vandara and now I gona make it in that font all it looks beter then all of them... thx
As you can see by the answers provided, it's going to vary based on the personal tastes of everyone. I say, as long as it is web-safe standard font and goes with your website theme/layout... then you're good to go! I use Arial sometimes, but with some layouts, Verdana looks best. Georgia even looks good with some layouts, and if you were going to go with Times, I'd use Georgia instead. Whatever you choose, what I do is make sure the fonts for headings are a different font than the body fonts... it's a subtle tip but really makes a big difference when you look at the big picture.
Fonts and typography is a very interesting subject area and millions of dollars are spent in working out exactly what is right for the context of the text. Next time you're out in a vehicle, take a look at traffic signs. What font are they in? What do you notice about them? Take a look at a newspaper or a book. Notice the font? Logos, headers and image-based text really should be sans-serif. It's easier to recognise at a glance or if you're just passing - sans-serif fonts don't take a lot to recognise or compute. Serif fonts are more involved, there's a lot more going on them but they're easier to deal with in large volumes and are familiar. For text body, I usually try something like garamond or georgia, it's clean and smart looking. Headers and logos, I lean towards Verdana or Tahoma.