RF Tx: what is better design by module(tx433) or using tranisstors?

i want to design a remote control for a device, i have seen most commercial transmitter for 433MHz designed with transistors and the Modules are not used....

i want my remote to have a good battery life as well as range (equal to commercial transmitter provided with gate openers etc) . plz guide me how should i start? with module or transistors?, if transistors plz if u can share the resources it would be great, and if with modules which module would be great to work with, i am going to buy them from china

search in this forum, there are a lot of posts.