Best method to build data entry forms in WPF?

When building WPF forms that are used for data entry (e.g. A bunch of labels next to a bunch of textboxes and comboboxes) I've seen two methods:

• Create a master Grid, divide it into two columns, and add rows with Height="auto" for each field and two rows for header and footer (and submit button), and each label and text box has their own row.
• The other method is to create a master stackpanel and inside it a horizontal stackpanel for each pair of label-textbox.

How do you design your data entry forms? I'm currently torn between the two methods, maybe there's an alternative that I'm unaware of?

EDIT: Henk said I should define best and I think I agree, by best I mean easiest to maintain, create, align and add or remove fields from as demands change.

So far the only criteria by which the grid is better is ease of alignment.