It is getting confusing having several different threads open asking 'is this a good part'? I understand you are trying to get as much info as you can, but try putting together some components based on what you will need for your loop that fall within your budget- this way we can get an idea of what you are trying to work with. Having a solid idea of your budget, components you want to cool, components you would like to use and loop design will go a long ways.
When it comes to reservoirs - a res is a res...it really just depends what you want and where you want it to go. Hell, you don't even need a res, but it makes it easier to fill and maintain a loop.
When it comes to radiators, you first need to determine how many watts you are going to need to dissipate from your loop. You do this by getting a sum of all components' TDP you wish to watercool. Use this number to determine radiator sizes you'll need. When it comes to radiators, most of the ones out there are good- just avoid any with aluminium. There aren't any good ones that contain aluminum, s you will be fine. FPI just makes fins more dense on a rad to increase surface area, but total improvement over a lower FPI rad is 10-15% max. No real need for them unless you want to buy loud, expensive fans.