Ah. The Gothitelle line, known for having one of the most broken abilities, Shadow Tag(which is banned but still cool). In addition, it is a psychic type, which I think is cool :).
Anyways, let's get to it, shall we?
Gothorita is probably your best bet, as since it has more offense, it can actually threaten some of the 'mons in the tier. Here are some calc examples, which I will also compare with the exact same with gothita.
- +2 252+ SpA Gothita Psychic vs. 252 HP / 4 SpD Eviolite Clefairy: 178-210 (51.7 - 61%) -- guaranteed 2HKO
+2 252+ SpA Gothorita Psychic vs. 252 HP / 4 SpD Eviolite Clefairy: 211-250 (61.3 - 72.6%) -- guaranteed 2HKO
+2 252+ SpA Gothorita Psychic vs. 252 HP / 0+ SpD Eviolite Golbat: 344-408 (97.1 - 115.2%) -- 87.5% chance to OHKO
+2 252+ SpA Gothita Psychic vs. 252 HP / 0+ SpD Eviolite Golbat: 290-344 (81.9 - 97.1%) -- guaranteed 2HKO
252+ SpA Gothita Psychic vs. 192 HP / 0 SpD Eviolite Ivysaur: 152-180 (49.1 - 58.2%) -- 95.3% chance to 2HKO
- 252+ SpA Gothorita Psychic vs. 192 HP / 0 SpD Eviolite Ivysaur: 182-216 (58.8 - 69.9%) -- guaranteed 2HKO
So, as you can see, Gothita can miss on some very important 2HKOs and OHKOs. This makes it challenging to justify. In addition, there doesn't seem to be any relevant moves that Gothita has, that Gorthorita doesn't have. Gothorita can use Eviolite better due to its better Special defense and Defense. This makes it, overall a better choice.
Warning
Gothorita is quite bad. I wouldn't use it. However, between the two, Gothorita is better.