Would appreciat
Would appreciate any advice novice divers going to Bali for the first time in September thinking of staying South and not trekking to the NW
@EmmCee66
People are both likely confusing you and possibly misunderstanding what you are actuallly asking.
If you are referring to Menjangan, Gilimanuk, and Permuteran as the "NW" then yes, it's not worth the trek for a first time visit. There is some good diving in this region (although not quite as good as it once was), but it takes a committment to get there.
However, you also mentioned "staying South" which would imply Nusa Penida, Nusa Lembongan, and possibly sites like Padang Bai, etc. These are great dive areas. For someone with limited diving experience (based on your profile), yes - it makes sense to "stay south." There is plenty of good diving in the region. However, these are also the most popular dive areas of Bali (and often crowded) so you may be on boats with 10+ other divers. Good to get this kind of experience, however not why many experienced divers come to Bali for.
Depending on how long you are planning to stay in Bali, consider a couple of days diving Bali's "North" (or more correctly, Northeast) coast. The Liberty wreck is worth diving (numerous times), and the life around it is incredible. This entire coast is a unique area, and one of the main reasons many experienced divers return to Bali as often as they do.
Many people plan "diving safaris" for Bali, because there are a number of interesting regions to dive. This does require changing your hotel, etc. because the distances make it inconvenient to dive from one location.
So yes, if you were going to pick one region to dive (and diving Bali for the first time), "stay south." However, if you want to see why Bali has as many diving fans as it does, try another region as well (I would suggest the "north" because of sites like the Liberty wreck).