When we started with toys it was all about clit vibes for 'effective' reliable orgasms. But as we got into g-spot and a-spot stimulation, dildos have advantages over vibes because pressure is more important than vibes.
Now we almost always have some of both going on. A dildo for internal and a clit vibe for external - although she occasionally likes two vibes.
The only truism I've found is that what she wants/needs is different almost every time. I use to think 'this worked last time - so lets do it again' - but now I think 'we did that last time - what can I do to mix things up'.
That's why we have dozens of toys - both vibes and dildos.