First post for me, but;
I have loved the Imperial Fists since I first got into 40k, to be fair I never really actually bought any models but I loved the fluff. Of course Primaris Marines... well damn take my money. One of the chapters I always loved and even more after 30k became a thing was the Imperial Fists closely followed by the Crimson fists. But my absolute favorite was the Astral Knights.
The Astral Knights did the impossible, but unlike another chapter who I shall not name, they did it but actually paid for it massively. Always thought if I was to collect a SM army they would be the ones. However I would have to collect them based around the World Engine. but now that Big G is running around handing out SM's left and right have a perfect excuse to bring them back