Best fonts combos for User Interfaces and Web Applications

[granmah]

Hi brothers! :)

I'm a UX/UI designer and I would love to know your personal preferences and recommendations relative to fonts for user interfaces, web applications and these kind of stuff

Helvetica. A lot of people use it, from Apple, to, for example, Mailchimp or Treehouse in their web app
Proxima Nova. An example is Skillshare, they use it in their web app, Smashing Magazine...
Arial. Of course, is everywhere
Open Sans. Is everywhere from Google to Gibbon.
Museo is also in a lot of places, can't remember now some examples
Lato. I personally prefer this over Open Sans

Any recommendation of fonts and fonts combos (serif/sans)???

Cheers!

[stradivarious]

I like the result of "Bree" with "Skolar"

[crackconcrete]

It really depends on what visual atmosphere you're willing to achieve, and also what budget you can afford.

Asymmetrical grotesks are everywhere at the moment (Mark, Circular, Aperçu, LL Brown), they're great set in bright colors with pastel backgrounds, and associated with classical serifs with an attitude (ITC Galliard italic, Commercial Type Lyon display italic, Spinoza…).

[grubstreet]

Depends on the UI style/desired atmosphere.
Another excellent choice is Lucida.
By the way, if you are setting small text (~12px) most beautiful serifs will perform badly, especially Garamonds (but I guess you can fiddle with Garamond Premier caption and see what happens)