thanks guys, lol yeah im no beginner of course, but the way homebrewing keeps changing and developing it would require fulltime dedication at the level of a job to really be an up-to-date expert
these are my personal thoughts on the hops i know, feel free to disagree:
EKG - gives medium bitterness per estimated IBU, excellent taste of herbal/hops, black tea, bright fruity. gives a lot of flavour
magnum - bitterning hop that feels very clean to me, gives slightly less bitterness than AA would have you believe imho. got light pineapple from it before
nugget - despite online descriptions, i find it gives a smooth and clean bitterness. woody, lightly spicy
hallertau (tradition? the ~4-5% AA one) - gives medium bitterness per est. IBU. herbal, spicy, floral.
tettnang - been a while since i used it, but similar to hallertau above but not as powerful a flavour
spalt - also been a while since i used it but for whatever reason it was my go-to noble hop. it is very mild and subtle. bitters as expected per IBU
chinook - slightly stronger than expected bittering per AA but not "harsh" imho. pine, "american", bright and lasting. i dont use it so much anymore
hallertau, tettnang and spalt are all interchangeable imho. you wouldnt ruin a beer if you switched them as long as the IBU was kept the same.
EKG is a hop i couldnt brew without. i cant think of a substitution