have you consulted with a plumber re: difference in set-up? installation costs? check out Ideabooks on this site: there may be some good ideas/set ups for you to guide you.

Yes I am working with a contractor and I can do either set up with the large space and plumbing, no issue there. Its room and aesthetics for the long run, I wouldn't want the bathroom to look dated in the near future. All my finishes are very timeless. I've been looking at idea books thanks.

Corner shower units or neo –angle showers are a great compromise when bathroom space is limited but a word or caution about shower enclosures. The shower stream tends to hit the door seals in a more direct way in a neo-angle shower and that leads to shower leak issues. Don’t skimp on the enclosure and think an inexpensive unit from a home center will work, because no matter how well it’s installed it will leak water on to the floor during use and the cheap plastic hardware causes alignment problems after a couple of years of use. Save yourself the headaches and go for a quality enclosure

This will be a custom shower not a big box kit.

Corner shower units are best when its stand alone unit when dealing with small and narrow sized bathrooms.
They don't need partitions that eat up space and you can get a complete unit without need of tile and it will come with its own shower door. Today you can find some nicely designed shower unit sets. If you purchase as a single unit, make sure it will fit inside your house and bathroom door is wide enough so the unit can pass through.
Most of the time they have a cut-off size to make sure it will fit into a standard door opening but I would make sure beforehand. Also you have to plan to have a minimum of 24" clear space in front of the shower stall this is why in many cases you have no choice but use the corner shower, where you allowed the minimum of 21" in front of the bath tub.
Other then that if along side of it you have a toilet it can work, but if you have a vanity, its a pain in the neck to clean on the side of it between the vanity and they unit itself, especially when bathroom is small and vanity is right against it.

Rectangular shower can be installed against any wall with a partition or between the 2 partitions, Rectangular shower minimum dimension is 30x30" where corner shower must be 32x32". Mobil homes are under different rules and I believe they can get away with a 29x29" shower.
With Rectangular shower, you have mo options as finishes go, you can do half walls with glass enclosure and have the cabinet right against the wall or partition, and its very easy to clean, etc.
One thing I would suggest is to stay away from put together laminated enclosures or shower stalls. I know manufacturers swear by its performance, but from my experience and coming across laminated products during remodeling projects, i.e kitchen refacing, Formica counters, bathroom stalls, etc they all fail down the road whether from heat, moisture or just from regular normal use...That should be about it.
Good luck

I would lean towards rectangular shaped shower . It's not likely to go out of style anytime soon. Here are a few pics, i hope this helps you !