Not sure if I should implement Bootstrap on my website for cross device scalability, grid system placement and basic animations, or just stick to raw CSS3... Any suggestions?

Okie with bootstrap all website looks the same now .
Anyhow . I switched to
http://materializecss.com
Not as popular as bootstrap. But it get the job done plus many out of the box classes are very useful.

Write your own shit, at least you'll learn something in the process.

Why not use a grid system?
http://neat.bourbon.io/

A custom framework in SCSS is way better than anything out the box because it's unique and suits you perfectly

@sylflo oh yeah if he is willing to customise it then yeah bootstrap will be fine too.The thing is lots of time when i open a random website the moment it renderd i can tell it's a bootstrap . U know ..!
Nothing against bootstrap i used it to many time too