Which would be better for this setup 3/8" or 1/2"

I've been working on a new water cooling setup the past few days. I got myself a Eheim 1048 158gph to replace my Rio 400 and it's going to be use inline.

I'm using the BeCooling 6.25"x5" radiator which is 3/8" and their Jagged Edge Copper Waterblock and thats is 3/8"

Now I don't know what size hose to use 3/8" or 1/2" and how much it will effect the flow rate or if I would get better cooling with 1/2 line.

Looks like I'll keep it with 3/8" hose. I'll just move it up to 1/2" when I get a bigger rad and the DD Maze2 block with 1/2" fittings.

you did not ask this question but:

if you wish to increase your flow rate,
do get rid of all those 90^ rt angle fittings

be cool

Rememeber that a simple design is generally the best one, don't use too much metal and pretzel it. Neat and simple will be the safest and most likely coolest.