Neo Gaiking is very good, tbh, one of the best remake series so far. Please don't mind the first slow episodes.
Shin Jeeg becomes good at midway, you should finish it.
Shin Getter Armageddon (the 90s one) is indeed a mess if you aren't familiar with the Getter series, but the New Getter Robo series is good and very easy to get into, check it out.