quartz, amethyst, and bismuth are three of my favorites but amber, tigers, eye, and selenite are nice.
also look into orgone generators if your into crystals.
my advice though is to find a crystal store and go and see what catches your fancy, different people are drawn to different crystals.
black tourmaline is also a good grounding crystal that i keep by my root chakra, I usually put selenite on my heart, tigers eye or agate on my third eye, quartz or bismuth on my throat and amethyst on my crown. I like to keep my orgone generator on my navel and will surround myself with other xtals. also meteorites seem to have some cool energy as well. Himalayan salt lamps also have very good energy when tripping.
Also the shape matters, for example xtal balls and pyramid shapes give off different vibes.
If you could elaborate on what type of energy your looking for maybe I could help more, but otherwise try to go a shop that sells crystals and just get what you like.