There are two kinds of controls that you can put on a worksheet, ActiveX controls from the Control Toolbox and Forms controls from the Forms (or Drawing) toolbar. Kevin, like others before him, asks how to decide which ones to use. I don’t know, but I’ll tell you how I decide.
In general, the two types of controls are similar in that they work the same way. That is, a textbox from the Drawing toolbar is a control in which you can type text. That’s fundamentally the same as the ActiveX textbox. Checkboxes of either type are used to select or deselect an option.
Obviously, a decision to use one or the other will based on their differences, not their similarities. The primary differences, for me anyway, are events and formatting. ActiveX controls give the spreadsheet designer a lot more flexibility when it comes to displaying or reacting to events of controls. Viewing the properties of an ActiveX control demonstrates how much more you can do with them than with Forms controls. Also, Forrms controls have one basic event, the click event, which you access by assigning a macro to the control. ActiveX controls, on the other hand, have a lot of events. The ActiveX combobox, for instance, has fifteen events.
All that flexibility comes at a cost (you knew it would). ActiveX controls carry a lot more overhead with them and have a history of being buggy.
Weighing the good and the bad, I always use Forms controls unless I have a specific reason to use an ActiveX. Forms controls are lean and mean and simple to use. If, however, I need a combobox to display a certain font, I have no choice but to use an ActiveX control. Similarly, if I need to avoid certain characters in a textbox, I’ll need the KeyPress event which is not available from the Forms textbox. So my advice, and my practice, is to use Forms controls unless I need functionality that only ActiveX controls offer.