Is there consensus about whether side-by-side or vertical alignment is preferred? For example, which of these two form fields provides a better user experience?:
You can read about a related question here:
In that question is linked this document, and here is the relevant paragraph from it:
Top-aligned labels tend to reduce completion times (how long it takes to complete a form) the most for familiar data (i.e. address, credit card, etc.) because they only require a single eye fixation to take in both input label & field. Top-aligned labels also work well for forms that require localization or long labels as there is plenty of horizontal real estate to expand/contract the label without negatively impacting the overall page layout. Top-aligned labels, however, do take up a lot of vertical real estate.
Also you can see this image from Smashing Magazine that shows the advantages and disadvantages of the positions of labels.
I do agree with the pros & cons of Top-aligned labes, however, the last conclusion that Top-aligned labels are only ideal for Simple forms sounds strange to me. Should not the type of labeling be consistent across the whole application, i.e. for the whole Internet Banking application that has both simple and complex forms?