is your pump built into reservoir?
because it pumps like through top in through the bottom if so if pumps not in res it shouldn't matter at all.

Im just trying to figure out if there will be any difference, other then needing a splash tube and keep liquid above that tube inside.

Using a monsoon mmrs custom reservoir   3 port top 5 port bottom . lot of flexibility in terms of hooking it up. I ve seen a lot of builds using return line at the top and im able to fill  the loop at the very top because my rad has 2 ports that are accessible so i shoildnt have an issue right? all i have to do is keep the fluid levels above the tube inside the reservoir? or will it be full already?

https://www.amazon.com/gp/product/B01LRC8VAA/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1  is the top cap
 
https://www.amazon.com/Monsoon-MMRS-SP-3P-Side-Ports-Three-End-Ports/dp/B01LRC8LDC/ref=pd_bxgy_img_3?_encoding=UTF8&pd_rd_i=B01LRC8LDC&pd_rd_r=a62f6686-727e-11e8-ab1f-1b6d2e476374&pd_rd_w=EXZwd&pd_rd_wg=0SZWm&pf_rd_i=desktop-dp-sims&pf_rd_m=ATVPDKIKX0DER&pf_rd_p=3914568618330124508&pf_rd_r=Z2HDV7672BPCK54XK208&pf_rd_s=desktop-dp-sims&pf_rd_t=40701&psc=1&refRID=Z2HDV7672BPCK54XK208  is the bottom
 
body is 150mm and its vertical
using a mcp 655 pump with custom top below the reservoir on the midplate.
 
ive seen setups and have the trident vortex piece that goes on the bottom. im just trying to find out if having inlet (return) at the top is okay, like is there any difference compared to standard outlet inlet being on bottom ( thats my currrent setup)   if i need to refill because of dissipation, can i use a port on the top of the res while its running like i can with my current?  will air get trapped more up in the rad?

What you are suggesting will work but would not be the best setup. Having the return at the top of the res with a radiator above the res and the flow return coming from that radiator to the top of the res will cause any air trapped in the loop to accumulate in that radiator as it is the highest point in the system (above the res and pump) in your particular setup. You would not be able to top off the system from a port on that radiator while the cooling loop is powered on as fluid pressure would push fluid out of that port if you opened it up or had it open while powered on (fluid would take the path of least resistance). The best way would be to have the return line from the top radiator go into a port in the bottom of the res as you have it currently in your Mod Rig pics. This would allow any air in the loop to get trapped in the res itself and allow you to purge any air trapped in the radiators\loop into the res by rotating your system while the cooling loop is running. you can then use a top port in the res as a fill port to top off the res.
 

Thanks for the info, i was actually thinking of just running the line from the rad above to the bottom of the res with the line parallel next to the res as im used to the same setup now just a different look.  Always makes me wonder why i see so many builds with that kind of setup though, i guess just for looks but maintenance is probably a pain.

Cool GTX
+1 good explanation jonkrmr
 
Also I would add that with only a 150mm body, any air in the return may not have room to separate before the suction side of pump recirculates the bubbles.

Yes, but if kernolsz28 uses a tube on that return port inside the res that extends up to an inch or so from the top of the res this should help reduce that effect (look at my res setup on my system in my Mod Rig. In my case on my res, the stock tube that came with it is not really tall enough but did\do not want to go through the hassle of draining my loop to put a taller tube in. maybe next time I drain for an upgrade ). I still get some air pulled back into the intake port on the res but it is minimal and mostly only micro bubbles which are prevalent in the loop when you are first filling\bleeding the loop. Letting the cooling loop run on its' own for a few hours after initial fill\bleed takes care of the vast majority of the micro bubbles. Granted though, the taller the res the less this effect happens.