Regarding D/P/Pt I honestly didn't play them much, that just weren't that interesting to me I guess? Also for some reason I found Barry irritating. I liked some of the Pokemon they introduced, especially Rotom and Garchomp, but overall for me I just didn't enjoy it that much. The lack of good fire types certainly didn't help either.
As for HG/SS I absolutely adored it, it's probably my most played pokemon game, the only issue I ever really had with it was that once you got to a certain point it really became a pain to level up. I played a nuzlocke run against a friend in HG and SS about a year ago and I was blown away by how much trouble I had leveling up for Red, it was just hours and hours of grinding. For a normal play through though I really enjoyed it and loved having my pokemon trail behind me. I really hope that feature makes a comeback at some point.