That honestly depends on what you're using it for. If you're battledoming with it, many people like to choose a Scorchio or a Pteri for their respective resistances to certain icons. Whereas, some people (like me) like chias for their fruit colours. Others are just weird.
I love Techos just because they looks so cool, laid back and carefree. But yeah if you're going for a battle pet, you want either a Scorchio or a Pteri for the resistences, or a pet like a Lenny for cheap species freezer & healer.
I like... having a blank pet sign =) They're so cute and they don't need to be fed x) Or I just like the old Grey Wockies X3