ring choice is personal preference. If you are not using a clip on NVD in from of your scope then pick the lowest rings that still give the objective bell of your scope some clearance above the barrel. If you are using (or plan to use in the future) a clip on NVD you will want a higher scope height to allow alignment with the NVD.
also not sure why you were only given 2 choices in height, you can choose different brands that should offer multiple sight heights. 1.075, 1.125, 1.185, 1.25… you will probably end up in the 1.125-1.25 range. but most gun shops will let you try the rings out in the store to check which you prefer. (if you post your location I'm sure somebody here could point you towards a place to do so.)
I usually choose rings as apposed to a unimount for cost reasons, however if you wanted to ad another 20moa giving you a 40moa base you could get a 20moa spuhr mount.
welcome to the hide.