I like PrintShop2 for Mac
I've had good luck with PrintShop2 for Mac by MacKier. Very versatile, very user-friendly, you can design from scratch or use their libraries of designs, textures, and text assortments.
BTW - I'd also just ordered PrintExplosion from Nova Software (two weeks ago) and have received no software... and no answers to two follow-up inquiries (like, "where's my stuff") I'd suggest you approach them with caution. I'm wondering if we're looking at vaporware. Anyone else had an experience with them?