Your choice of molds realy depends on what your target market will be. For IPSC you are looking at 9 MM, 38 Super .40 S&W/10 MM and 45 ACP. I think Magma makes some of the most popular designs for this sport. For cowboy action shooting there is a growing market for more traditional designs and softer bullets but also light weight bullets in the big 3 ( 38, 44, 45). The softer bullets tend to have a higher regect rate due to less tin and antimony. Also you will find some bullets out there for the black powder shooter with special lubes like SPG. I feel that Lyman and RCBS offer the best designs for the traditional market without getting into really expensive molds. Then there are the hunters and silouette shooter where heavy gas check bullets are the market.
All this said, if you want to do something really special you should look at Balisti-Cast's line of molds, they bought the fine Hensley & Gibbs mold line and offer casting machine molds.