All of them?
We use specific malts when we are trying to get a style “right” but I see no reason you can’t make a nice lager with Maris Otter or Pale Malt or why you can’t make a nice ale with Pilsner Malt.
Depends on what type of lager. I certainly wouldn’t use GP for a German pils. I think a pils malt would work well for both. You can add specialty malts for different styles.
A lot of lagers are dependent on their base malt, so there is no universal answer. But a good Vienna malt would work as the base for the majority of ale recipes, I think.
I have made lagers with a variety of base malts (Maris Otter, Golden Promise, Pale Ale, Viking Pilsner Zero (LOX-free), Best Malz Heidelberg, American Crafted two row malts) coupled with Munich or Vienna, typically. The lagers would best fit under the International Pale Lager category, if I were pushed to pigeon hole them. I think the English malts are pretty flavorful in a lager - something unique and expressive.
If you are aiming for pilsners as a regular part of your repertoire alongside ales, I would say that pilsner malt is going to be your most versatile option. You can always add character malts to round things out.
Personally, I would go with a nice domestic 2-row – I’ve made some killer pilsners with that (even if they’re not completely true to BJCP), in addition to a variety of ales.
At my home brewery, I keep bulk 2-row and pilsner, because those fit 90% of what I brew. When I was on my English ales kick, I had some Maris Otter, too. Brewing habits change over time!
50/50 works for me. Especially when my wife tried to organize my Pils and Rahr malt before I stuck on labels on the pails. I still can’t tell which one is which so I am using both.
also re: OP - pilsner is the most versatile one i use as i’ve used it in american ales, obviously in all belgian ales, and in lagers. if i were to buy a sack i’d buy wesyermann pils or something
I don’t recall if I’ve used that one or not. If it’s significantly less expensive than Weyermann, it might be worth a try based on my experience with their other malts.
I definitely get that from their Floor-malted Bo Pils. I haven’t used enough of their other pils malts to say for sure that I get grassiness from them as well.