I haven't tried it yet, but I think the eroscillator would be one of the best. I love my Salsa and Moka. Dunno what else I might recommend. I would say siri, but it's not waterproof and moka is. Plus Moka can be leveraged to add pressure.
I think if you are going with a first vibe I would definitely not pick anything extremely powerful. I would go with something made of silicone with multiple settings and vibration patterns, so she can figure out what she likes and doesn't like. I would also go with something small so it won't be intimidating. I would pick something like MiMi by Je Joue, Siri by Lelo, or Life by leaf. Not all of those recommendations have multiple patterns, but it should give you and idea of the style I'm talking about . I hope it helps!!
I think every women should have at least 1 bullet, 1 rabbit, preferably waterproof but that might just be me, and 1 glass toy vibrator. I know most people dis agree with me about the glass one however I add it to the list because its easy to clean, you can use them with their vibs in or take it out if you don't want it that time, they are pretty, and for the most part don't break the bank buying them.