Ghost in the Shell is always a contender in that area. It's mostly cybernetics and cyborgs there but a few other cool things too.
There are a few Appleseed movies/OAVs which are pretty high tech. Though the art style changes a lot between each version so that can be a bit distracting. (Like one of them uses this cell shaded 3D look which is kinda odd looking.)
For giant robots
- Gundam is probably the biggest franchise.
- if you don't mind some supernatural elements then Code Geass: Lelouch of the Rebellion is an option.
- if harem elements don't bother you then Infinite Stratos has some cool stuff.