I tend to avoid variants, except for issues that look like they have the potential to become key issues, but large press runs. For instance, I purchased a WD 100 Adlard sketch variant. WD 100 is a potential key issue for multiple reasons, but has a HUGH press run, but by buying the 1:200 variant I know at least that cover is limited to about 1800 copies.
Or sometimes if I just like the cover. Splurging for 10 or 15 bucks to get a cover I really like is nothing compared to some of my other purchases.